It says here on your resume that you are familiar with Matlab. That is an important tool that we use in engine management systems work at ABC Corporation. In your view, what's the best thing about Matlab?

"Anyone familiar with Matlab has probably typed 'why' into the command window at least once, after typing 'who' so many times, just out of idle curiosity. It might not be very productive to sit around the computer monitor with your friends laughing at the random answers Matlab generates to the question 'why,' but it's fun, harmless, and very true to what engineers think is funny. But more seriously, yes, I have done several school projects using Matlab and Simulink. It might not be my first choice for making a simple home budget spreadsheet, but for any technical task requiring repeatedly processing large amounts of data in flexible ways, for building simulations of control systems and even creating autocode from them, it's a good tool. I am open to learning any additional tools that ABC Corporation uses, but already knowing one such powerful tool is a good foundation, and it sounds like you are already using Mathworks products, so I could hit the ground running on that score."

Everybody knows that the best thing about Matlab is the random answers you get when you type 'why' into the command space window. If the interviewer wanted a completely serious answer, they would have phrased the question differently. You would not be blamed for a completely serious answer, but given the phrasing, you are being invited to show that you really ARE familiar with Matlab - and that you have a sense of humor. A sense of humor is not a requirement for being a good engineer, but an interviewer is entitled to consider what kind of personality you bring to a group. When you've dispensed with the humor in the question, you can round out your answer with a more serious description of what you see as Matlab's good points.

When you have a choice between walking over to a colleague's desk, phoning, emailing or instant messaging to communicate with them, which would you choose and why?

"That depends. I have never met or talked live to some of my overseas colleagues. We communicate by email or IM. With some folks, it's all business, and that's ok. Their personality and capabilities still emerge over time, but you do have to be extra courteous and careful in these exchanges to avoid misunderstandings. Written communication is often best in these situations, because either you or the person on the other end may be functioning in a second language, and writing allows you more time to be more precise. For local employees, it still depends. If it's a private or very complex matter, or an open-ended one that involves alternate generation of ideas and mulling them over, then I am going to walk over to their desk. My next go-to communication method would be IM. You usually get an immediate response, and while you can get into side conversations, no one is offended if you stick to the matter at hand. If you just have a quick question, IM is a great tool. These days, I'm probably not going to use the phone unless I know that the other person prefers to communicate that way. Some people don't type very well, or don't feel that they come off well in written communication. They'd rather talk on the phone. On the one hand, that usually ends up taking longer, but on the other hand, it allows you to nourish your bond with a colleague. I would use email more for formal communications where I want some documentation of the conversation, or when something is too complex for IM, is not time-sensitive, and there is no reason not to give a person the time he needs to consider his answer. I think a person should be sensitive to the benefits of face-to-face conversation. You have to balance that against the instant gratification you get from IM exchanges."

What a silly question, right? Maybe not. Maybe this question tells the interviewer something about your personality. There is no one right answer for all situations, and the mature communicator will describe the limits of each type of communication.

If you were interviewing someone for this job, what one question would you be sure to ask them?

"I would want to know what the person loves most about being an engineer. For me, everything else flows from the answer to that question. A candidate can talk about their love of learning, their love of creating actual, physical objects, their love of being part of an effort to produce products that may improve the standard of living or protect the environment. If they show me authentic enthusiasm about their chosen profession, then I believe that they will have the energy and desire to learn everything else they need to know to be successful."

Your answer to this question tells the interviewer something about how you view the world. What is more important for judging a person's fitness for a job - his specific technical knowledge or his general behavior and personality? Either one is a possibility. You may view a complete command of job-related technical detail as most important. No one can say this is wrong, but then you have to be prepared to deal with a wide range of personalities, some quite difficult. If you choose behavior/personality as the best differentiator between potential success and failure in a job, then you may need to be prepared to deal with a wider range of technical capability or knowledge.

Earlier, I asked you to describe how an oxygen sensor works. Your answer was not correct. How would you go about remedying this lack of knowledge?

"Could you say more? Specifically, which part did you think was wrong, and what would be a more correct way of putting it?"

An interviewer could ask you how you react to criticism and listen to you try to impress him by going on and on about how well you respond to having your work challenged... or he might just interject a little friction into the interview and see for himself how you react. Do you fold even if you are correct? Do you simply resist? Do you think it through? There is almost nothing that good engineers get more of during their careers than criticism. It is the basis for disaster and error prevention as well as potential product enhancement. Of course, it is usually called 'constructive criticism' or a 'design review,' and in a good work environment it IS done in a positive manner and without blame. But it can still be challenging to be critiqued, even politely. Are you mature enough to handle it? You want your answer to acknowledge the possibility that you could be wrong while not ceding the field until you know more. With a question like this, you need more information to know whether you were actually wrong at all, whether you should diplomatically defend your answer and allow the interviewer to save face by saying that you think it was correct, but you will go back and take another look; or whether you really DID have a gap in your knowledge. In that case, you might thank the interviewer for correcting you and wryly point out that you still have a lot to learn about the subject.

What do you need from your boss in a work setting, and what do you expect from your peers?

"I am pretty good at working independently. I am a self-starter, and I don't like being idle. So I don't need someone constantly looking over my shoulder to see if I am doing what I am supposed to be doing. I also wouldn't be super-happy to see the boss getting involved in every detail of my work. Of course, I am really talking about that stable point where I have learned what I need to know to make the kind of contributions that I believe I am capable of. At first, I realize that I will need instruction in the company's methods and products, how to best fit in to the culture. But once that phase is complete, I expect to work independently within the priorities I've been given. I'd like to have the boss check in with me from time to time to see if I need anything that I think can help me do my job better - training, for example. I expect to check in and have him either give me his current list of priorities for my work, or to sign off on the list I suggest. I expect him to give me feedback about how I am doing so that I can keep improving. Lastly, I expect my boss to give me opportunities to grow and advance, that he won't, for example, refuse to allow me to move to other opportunities in the company just because it is inconvenient for him to lose whatever expertise I have developed. From my peers, I know that I would initially need a lot of help ramping up to full competence in this job. I would want to feel that I could go to them with just about any question, whether it was technical or some other job-related piece of information, and know that it would be received with patience and respect. I would expect to do the same for newer employees once I had been around for a while. "

As with many interview questions that examine personality characteristics, there is a range of answers that indicate that the interviewee is a normal, well-adjusted human being. Saying that you need nothing at all from your boss or peers and hope to see as little of them as possible; or that you really would like to talk to your boss every day, and that your peers should be available at all times for your questions - these two ends of the spectrum might raise a few eyebrows. Be honest, but be realistic about how company hierarchies need to function.

I see from your resume that you were part of the on-board diagnostics team at XYZ Corporation. What method of diagnosing a stuck-closed charcoal canister did you provide to our mutual customer, ABC Corporation?

"I would not be comfortable discussing the details of the work that we did with ABC Corporation. However, I'll be glad to outline the general principles involved in diagnosing a solenoid that is stuck closed. Would you like me to do that?"

The interviewer may be testing your integrity to find out whether, in your zeal to ingratiate yourself with him, you reveal confidential information from your previous position. The other possibility is that he is fishing for information. Can you blame a guy for trying? Yes, actually, you can. The problem for you is that you may not be able to establish the true motive for the question, no matter what the interviewer says. You might want to keep that in mind. One thing is for sure, you are not telling the interviewer what diagnostic method your previous company sold to ABC Corporation unless it is already published public knowledge. Being direct in your answer will show that you understand this as a question about your integrity, whereas deflecting or using plausible deniability ('well, I wasn't that close to the project') does not send a direct message to the interviewer.

What experience do you have working with international suppliers?

"Since I am applying for my first job out of college, I do not have any work-related experience with international suppliers. However, when I decided to become an engineer, I decided to also begin studying Chinese, because China is the world's largest market, as well as being a supplier of both labor and parts to companies around the world. I had already studied Spanish in high school, and I have maintained my proficiency in that language. In this day and age of high-speed internet, I would expect to have a number of means of communication with far-flung personnel, whether or not I was able to travel to their sites and meet them in person. Obviously, that's ideal. But between email, telephone connection and video conferences, there should be no reason not to be able to function almost as if you are in the same office. One thing I learned by studying other languages is that just because you can't spell an English word or use the wrong plural or verb tense doesn't mean you are dumb. Expressing yourself in a language that is not your own is hard work for most people. I know that you have to focus on the message that the other person is trying to convey, and I know that it helps to be clear, and to approach everyone with respect. That is how I would handle contacts with international suppliers if I were hired for this job."

Whether or not the company you are applying to is, itself, a multinational corporation, it will certainly have customers and/or suppliers in international locations. This question gets at whether you have a realistic view of working with others in overseas locations, which may involve online phone calls and meetings at odd hours of the day, difficulties understanding a person who is struggling to express him/herself in a second language and cultural differences in how to express agreement or opposition to a proposal. If you do not have work experience yet, you can find another way to show you understand what it means to have a customer base, workforce or supply chain spread across the globe.

I see here that you graduated 10 years ago with a Bachelor of Science in Mechanical Engineering, and that you have been employed at one company since then. What has been your approach to staying current on technical developments in your field?

"I never got a chance to go back to graduate school. But in place of that, I have spent the last ten years learning things that are not taught in schools anyway - like when to abandon a fruitless line of experimentation; when to push your boss hard for what you believe in; how to accept criticism and let it make the final product better - and a whole lot of technical details of my projects that are confidential. At the same time, you bring up a critical point. It is vital to keep refreshing your skills after you leave school. I am a member of SAE. I attend my local chapter's meetings, giving me a chance to talk to other automotive engineers regularly. Of course, with SAE membership, I have access to their publications, and I do leaf through them every month. Our company had digital access to all of SAE's publications, and I frequently consulted the SAE literature to learn about advances in emissions control systems. In addition to that, I have attended the SAE annual conference some years, and I have served as a peer reviewer for conference technical articles. Aside from SAE, my current company has offered the chance to take some short courses - on Matlab, Simulink and autocoding, for example - that are relevant to engine controls work. I have also studied problem-solving approaches like Shainin Red X and Green Y. Those are just a few examples. I take continuing education seriously. I want to take advantage of all the research being done out there to help with my own work."

Skills do fall behind if they are not maintained. Just try looking at your college textbooks and see how many of those formulas look like anything except a bunch of little Greek letters whose significance you don't remember. As a person with ten years of experience, you do have value to offer to companies you might apply to. You know how to get things done, how to fail until you succeed, how to learn what you need to know. If you haven't taken any continuing education courses, you will have to answer this question carefully, emphasizing what you have learned on the job. Sit down before the interview and list all the short courses you either had to take or chose to take, or other ways you tried to keep current, and be prepared to talk about how those activities enhance your value for the job under discussion.

You speak English very well. I just hear a slight accent. Where are your parents from?

"Thank you for saying so. I have worked hard to make sure that my communication skills are good. You may be wondering if I am authorized to legally work in the US. I am, and I can provide proof of that, when needed."

This is not an acceptable interview question. It opens the interviewer to being accused of discrimination based on national origin. Most interviewers know this. Your task is to gracefully shift the terrain back to the only acceptable questions which are, 'Are you authorized to work lawfully in the USA?' or 'Will you need visa sponsorship to continue working in the USA?'

Tell me about any experience you have with on-board diagnostics.

"I don't have any experience with on-board diagnostics other than a few times when the MIL light has come on in my own car, and then finding out later what the diagnosis at the dealer service center was. However, I am aware that the position that I am interviewing for is for an entry level engineer to work on diagnostics. So I have read a bit about it in preparation for our chat today. I know that the purpose of on-board diagnostics is for the engine management system to constantly monitor whether all the elements of the emissions system are working properly. I know that the diagnostics check for circuit faults like voltage high or low, or open circuit. I also know that there are classes of faults detected by rationality diagnostics, where the software can assess whether the device is giving a result that doesn't make sense for the current operating conditions. In reading about it a little bit, I learned that if the criteria for passing a diagnostic are not met for a certain length of time, a malfunction code is set, and that with a scan tool, one can read the malfunction code and have a pretty good idea where to start in troubleshooting potentially bad hardware. I imagine that one of the biggest issues in designing diagnostics would be avoiding false failures and false negatives. It sounds like a really challenging field of work."

If there is one piece of advice that cannot be given too many times, it is this: whether or not you have any experience with a particular technology, at least know the vocabulary. Humor in an interview can be extremely dangerous, so consider carefully whether an answer like this one is really the best plan: 'You mean besides putting a piece of electrical tape over the MIL light on my dashboard when it comes on and won't go back off?' It's usually better to play it straight.

Are you more interested in hands-on work like calibration and testing, or more software-related work such as creating controls algorithms and software?

"I think it is important to ultimately have experience in both areas, both controls work and hands-on. I love creating control algorithms, because I get a big charge out of seeing a car do exactly what I told it to do. I love analyzing the data that goes into it, and figuring out how to manage a function efficiently while still considering and planning in the software for things that might not go as expected. But at the same time, when you are just pumping out software with features that seem convenient to you, and never getting your hands dirty with trying to make it work in a real car with the interactions of all the other subsystems, and you have never tried to calibrate your own software from scratch.... well, I think you can get a little bit out of touch. So while my preference is controls development, I understand the value of both functions, and would eventually like to get experience in both."

It takes a village to develop an engine management system, so there is no right or wrong answer to this question. But you might spend a few minutes reflecting on the question, because if you are applying for an engine management system engineer's position, both you and the company will want it to be a good fit.

Are you able to travel when needed? As the job description says, up to ten percent of your time may involve travel, and it may be for several weeks at a time in remote areas. Would that work for you?

"I'll have to admit that I am a bit of a homebody. I understand that travel can sometimes be required to do a job properly, and I am willing and able to travel when required. However, I would not be pushing for opportunities to travel just for the sake of doing it."

No matter what job you are applying for, you should already have thought through whether you are willing or able to travel. Calibration engineers go on test trips which may last for a week or two at a time and are likely to be physically uncomfortable, since the objective is to test cars in garden spots like Death Valley in summer (heat) and Kapuskasing in winter (cold). If adventure appeals to you, you will really love this, but if not, answer with care. Another source of potential travel is the rare occasion when a critical software error is discovered after the release of a product. This can lead to squads of engineers sent to sites to re-flash hundreds or thousands of vehicles, under time stress. Of course, more mundane travel may also be called for in support of customers or joint projects where access to specific hardware is needed. Travel is not a major feature of the jobs of most automotive emissions system engineers, but the need does crop up from time to time.

What experience do you have writing requirements for hardware or software components? How do you approach it?

"I have not been responsible for writing requirements for a project or component so far. I have been the one on the receiving end of the requirements, trying to satisfy the specifications. Looking at it from that perspective, and attending project team meetings, I know that it is important to first write down and have the team agree to the high-level goals of the project. For example, suppose you are responsible for the engine management system for a new powertrain that is supposed to meet LEV III emissions standards. That's one high level goal, and you need to then set the engineering targets for those emissions. There may also be cost goals and other goals that have to be taken into account, hopefully ones that are not inconsistent with each other. But everyone has to acknowledge the primary goal, providing a compliant EMS on the date that the customer has requested. From there the hardware and software subsystems have to develop their own sets of quantifiable functional requirements to meet their parts of the goal. Now, obviously, I am describing how requirements flow from the top level of a project downward into smaller systems. But the same philosophy holds all the way down to, say, fuel control. What are the functional requirements for the fuel control? Should a linear or switching oxygen sensor be used? Does the air/fuel deviation from stoichiometry need to be controlled more tightly than in the past? What is the new number? Many of the requirements will be well known from previous projects, and it will pay to focus on the new and changed requirements. But for sure the only way to avoid disappointment and changes in the middle of the project is to write down all the requirements and track them. And then there will still be changes in the middle of the program, this we know. Structured project management approaches try to formalize efforts to create and track requirements, and even though all that paperwork seems annoying, in the end, it always turns out to be important.If you like, I could also talk about what goes into the requirements for an individual component or algorithm change."

The first brick in the foundation of a successful project is well thought out requirements. These requirements flow down from the project level to the level of individual components. You should be able to articulate how you would decide what these requirements should be, even if you've never had to do it yourself. You can think this one through and come up with a good, logical answer. One key is that the requirements should be quantifiable, so that you know whether or not they have been met.

What part of your previous job did you like best?

"I loved the sense of accomplishment I got when I tested a new component, figured out the best way to determine whether it was an improvement or not, evaluated the data that I took and could show clearly that it was a winner. That's a potential product. That's a win for the company. Obviously, the goal is that it should go that smoothly. But an equally exciting part of engineering, and really, the crucial part for making progress, is being able to solve problems. There's nothing to compare with the satisfaction of unravelling a mystery about why a component or a system didn't work the way it was supposed to and then fixing it. I guess you could say I didn't mind the hard and sometimes frustrating work to get to that feeling of victory."

This question is an invitation to highlight what you love about engineering, whether or not your last job gave you enough opportunity to do that. If you really want the job you are interviewing for, you will tailor your answer to point out to the interviewer that what you like to do dovetails neatly with what the job on offer requires.

Are you more interested in theoretical research or applied research?

"I got a PhD because I thought it would prepare me well for just about anything. I would have a narrow expertise about one thing, but a broad scientific foundation. As you can see, my dissertation involves quite a bit of actual lab work, and I love working in a hands-on environment. The description of the job that I'm interviewing for here today says 'Advanced Development.' That sounds perfect to me. It combines the opportunity to use all the engineering and scientific discipline I learned in school with an opportunity to pursue specific technology goals and useful products."

This question is most relevant to PhDs, but could apply to interviewees at any educational level. The interviewer wants to avoid a mismatch between your expectations and the reality of the job on offer. There are few things sadder than a theoretician trapped in job where he is just implementing someone else's basic science discoveries, or watching a guy who loves taking the basic science and making it reality trapped in a labyrinth of speculative modeling. You have nothing to lose by being honest and everything to gain.

What made you decide to leave ABC Corporation?

"I worked at ABC for five years. I learned a lot about the automotive industry, and I learned - I won't say I learned everything about my job function, but I learned enough to be highly proficient at it. I would like to take on a different challenge, and while I did ask the question, it didn't look like there were any opportunities to change job functions at ABC in the foreseeable future, so I decided to look elsewhere. Here I am. I want to work on more than just one component of an emissions system. I want to be a part of making the whole thing work. I want to broaden my base of knowledge. I find that challenging, and I think it makes me more valuable to the company I work for"

In all probability, 'I hated my last job' is not the tack you are going to want to take here, even if it is true. Surely you can put some lipstick on that pig. It might be as simple as thinking through WHY you hated your last job. Just tell the interviewer what you want out of your next job, without speaking negatively about your last one. If you worked at your last job for less than three years, this explanation needs to be pretty convincing.

A friend of yours loves old cars and race cars. He tells you that he has read some articles that say that when you consider every part of the lifecycle of the electric vehicle, it worse than an internal combustion engine vehicle. What do you say to him?

"I don't necessarily have every fact about the relative environmental value of electric cars loaded in my mind and ready to go in case I need to discuss the topic with someone. So I would be in a weak position if I simply started debating the subject, because I would feel that I didn't have the facts I needed to form a knowledgeable opinion. I know enough to know that the statement is probably wrong even if you consider the full life-cycle emissions, but I would want to double check.If this were a debate with another engineer at work, or even a friend who was an engineer, I would assume that this person would respond to information as we have been trained to do - evaluate the source, evaluate the information, seek as much additional information as we think we need, always paying attention to the authority and expertise of the source (as well as whether it makes any sense). I would ask the person what information they based their opinion on. I would tell them that I didn't have a formed opinion on it, but I would read up, and that I would love to continue the conversation after studying the question a little for myself. Then we could just let the chips fall where they may, and may the person with the most credible data win.On the other hand, if this were, say, a childhood friend, a person that I know well and value highly as a friend, I would be thinking fast about whether it was worth getting into it at all. His passion and love of his traditional cars would likely get in the way of a real exchange of information, and it might not be worth it to me to try to change his whole world view. I might just say, 'Mmmmmmm,' in a non-committal way, and change the subject.If I DID want to tackle my friend's misperceptions, I would probably start by agreeing with him that considering the complete impact of a technology on the environment is a smart way to go, and then I would ask him where his information came from. As with the engineer scenario I mentioned above, I would want to pause the conversation to find out more about his sources, but when we discussed it again, I'd be trying to ask questions to find out what his real concern was. Is it really electric vehicle emissions? Or is his concern that internal combustion engines will be banned, along with racing? Or maybe it's that he doesn't feel that he could change over from racing IC engine cars to electrics. Perhaps it's wrapped up with political views that I have no prayer of changing. If I tackled this at all, I know it would be a delicate, long term project."

You can treat this like a technical question, or you can treat it like the slightly more complex question that it is and tell the interviewer how you would communicate information to someone who already has a clear position that doesn't necessarily correspond to the facts.

What formal problem-solving and process improvement methods do you use?

"I have been trained in a number of quality programs, starting with Phil Crosby's 'Quality Is Free,' accompanied by his mantra, 'Do It Right the First Time.' It's never been my experience that quality was actually free, but we all got the point: the money you spend to get quality may be cheaper than paying for the warranty returns for a poorly designed or made product. In the years since, I have taken several Taguchi Robust Engineering classes. I found these valuable for the statistical tools they provide. When I need to do structured experiments, I get out my Taguchi experimental layout tables to use as a guide. I've heard of Six Sigma, but I have more familiarity with Shainin's Red X and Green Y programs. In fact, I have earned apprentice status in Red X and journeyman in Green Y. Red X is directed more at problem-solving, providing a structured method of defining the problem and then, as they put it, 'splitting the dictionary' - using the clues in front of you to help you go down the right branch of a decision tree to find the root cause of the problem. Green Y is my favorite, because it is a proactive method. With Green Y, you are not just trying to fix a problem that already occurred, you are using a process that helps you to design it well in the first place. It makes you think through the functions of the part or system and helps you to use statistical tools to optimize the functional performance. I am comfortable with these tools and ready to learn new ones that your company may use."

In the long history of engineering, there have been many attempts to package common sense, organizational discipline and statistics into marketable 'systems.' If you are a recent college graduate, you may not have heard of any of them. But if this is not your first rodeo, you may know quite a few quality program buzzwords. Mention as many as you can think of, then expand a little on one that you have personally found to be of value.

A customer is complaining about an engine stalling problem. Two engine management system solutions have been identified. One requires a change in your area of responsibility. The other would require a change in another subsystem. What should you do?

"It seems like there are several things to consider. 1) Are the two solutions technically equivalent? 2) Does the customer have a preference between the two? 3) Is one solution significantly more difficult or time-consuming to implement? 4) Is it more feasible for one or the other of the two subsystem owners to accomplish the task quickly, based on their workload and priorities? From your brief scenario, we don't have the answer to any of those questions, but those are the things I would want to know before either volunteering to do it myself or trying to get the other guy to do it. Hopefully we could work it out between us, but in some situations, the right thing to do would be to lay the facts in front of both of our managers and let them make the call."

Every overloaded engineer on planet Earth immediately says, in the privacy of his own thoughts, 'Make the other guy do it!' The reason they do not express this thought is because they know it's not the best way to arrive at a decision. There are many possible factors to consider. Surface the ones that seem objectively important to you.

You are testing some new engine control software on a vehicle. You are ten miles from anywhere and the car quits running. Now what?

"I've been stranded on the road a couple of times in my old clunker, so I have some idea what that's like. Of course, I didn't have any control over any of the systems in my own car, so if my test vehicle dies, maybe I am further ahead than usual! If I'm lucky, the car died in a place where I can get it far enough off the road for me to safely check out a few obvious things. Maybe I can read the diagnostic codes to get some idea what might be wrong. I mean, fuel, air, spark, right? Which one am I not getting? Of course, I know that it is more complicated than that now, but that's a way to organize my thinking. I would ask myself what has changed on the car. Is there any new hardware? If I didn't install any, maybe someone else did. I would call back to the garage technician and ask. If I could identify any changes that might cause the car to quit running, I would check and see if a wire fell off somewhere. I'd ask myself if the software changes I had made could have caused this problem. Hopefully, the answer is no, because hopefully I tested the software on a bench before I put it in the vehicle. But I can't exclude this possibility. If the car isn't completely dead, if I get battery power when I turn the ignition on, then I would try to reinstall the last known good software, see if that helps. I don't like to admit defeat, but the wisest thing to do may just be to call the towing company and go back and deal with the problem at the lab or garage."

If you have ever worked in the engine management systems field, you already know what to do. You would never get this question. But if you are a new college graduate, the interviewer wants to learn something about how resourceful you are by posing this scenario for you. Think through the options for a second, then lay out the possibilities and how you would step through them. You can assume that this has happened to any interviewer who asks this question, and in the back of his mind, he's thinking, 'Never leave home base in a test vehicle without the towing company's phone number in your cellphone contacts.'

Your customer has asked for a specific software change that you do not believe will solve the very real problem that they are experiencing. What do you do?

"Let's assume for the sake of this answer that the defect is not safety-related. I am mindful that customers often have ideas that are very logical from their point of view, but may not take all the complications of an engine management system into account. First, I would analyze the data that the customer provided with their complaint. If they did not provide any, I would ask for some. If I concluded that their solution would not address the root cause of the problem, I am guessing that an alternate possibility would suggest itself to me as I looked at the data. I would write up my suggested solution and distill the two solutions down to a brief description of the problem, the problems with the customer's solution, how my solution would mitigate the complaint, and then ask my manager what approach would best meet our commitment to this customer. Going the extra mile without charge might be a good long-term strategy. On the other hand, we might be further ahead quoting my alternative if we think they will listen. If the power relationship is such that 'customer says frog, we jump,' then maybe it is better to just implement the customer's solution. I'd want to at least note in the documentation that we did not have full confidence that their solution would work. I would make my recommendation, but the strategy that is selected is up to my boss. Having registered my objections, I would then do as my boss asked, no matter how dumb I thought it was."

This question may be a bit harder for a recent college graduate to answer. You might think the best answer is to simply ask your boss what you should do. But that's the last step in the process. The first step in the process is to make sure that you can outline a realistic alternative to the customer's request. Your answer should lay out a strategy of evaluating the problem, analyzing why the customer's solution wouldn't work, detailing your own potential solution, and only then approaching your boss for guidance. Finally, acknowledge that the final decision is in the boss's hands unless he delegates it to you.

Tell me about a time when you did a car or home repair. What was it, how did you proceed, and how did it turn out?

"I spent my childhood handing my dad tools as he did home repair projects, did mundane auto repair and rebuilt a race car engine. At the time it seemed like a bit of a chore, but now I realize how lucky I was to have a chance to get comfortable around tools of all kinds and to not be afraid to use them. I'll never forget the first time my dad handed me a starter motor and said, 'Here. Go replace the starter motor on the car.' By myself. I was sixteen. First, I had to FIND the starter motor on the car, since I had not previously been fully aware that there even was such a thing. Then I had to find the right wrench. There were just three bolts, but I dropped that frigging wrench through the engine and crawled under the car to get it about fifteen times before I got it all figured out. I'm sure my dad knew that it wasn't the most complicated care repair job, but it was a great place to start, and I did it. For years I did my own car repairs, and if you can name it, I replaced it."

Especially in a job where you may have to install your own test components on cars or interact with technicians who do, and where you may have to set up various kinds of test equipment and trouble shoot it, an interviewer might like to know whether that comes naturally to you. This kind of question lets the interviewer know what kind of practical knowledge you bring to the job. The sample answer below is from a person who takes a lot of pride in their automotive experience and is confident about vehicle work.

What would be some of the considerations an engineer would need to take into account in managing fuel and emissions control for CNG as a fuel instead of gasoline?

"I haven't had a chance to be involved with a CNG program, but I did take a class on the fundamentals of internal combustion engines, by which I mean fundamentals of gasoline-fueled engines. In a gasoline engine, the fuel is stored as a liquid and passes through the fuel system to the injectors as a liquid, and the injector atomizes the liquid so that it can vaporize to be burned. The obvious difference between that and CNG is that CNG is stored as a gas, transported as a gas and metered into the engine as a gas. So the fuel storage would have to be as high-pressure gas cylinders, and the fuel lines and injectors would have to be large enough to carry enough fuel to the engine in already-vaporized form. On the good side, the problem of vaporizing liquid fuel under cold conditions, like engine start-up, disappears. CNG is already gas, so as much gas as enters the cylinder will burn (assuming there's enough oxygen). This would improve cold start emissions compared to those from gasoline. The oxygen sensor shouldn't have any trouble detecting the stoichiometric point of the CNG, so fuel control should not present any fundamental new problems, but the stoichiometric point would be different than for gasoline, so that might produce a need for some changes in calculations. Since the fueling system would be so different, I guess you wouldn't need a charcoal canister - no liquid fuel vaporizing and trying to escape. I would be thinking a lot about the safety aspects of potential tank rupture and leakage, there would need to be new diagnostics for that, and of course the gas cylinder pressure would have to be down regulated as it leaves the tank, or at least, for sure before it reaches the fuel injectors. I am sure there is lots more to it, but these are a couple of the things I can think of right away without having had a chance to really delve into it."

This is just a straight technical matter. Regardless of what technical question you are faced with, if it is directly relevant to the company with which you are interviewing, you owe it to yourself to do some homework beforehand and to know at least SOMETHING about that technical area. Study up. If it is clearly more of a random vehicle systems knowledge question and you don't have any specific knowledge or experience on the topic, you can still make a pretty good answer just by thinking it through and using your general knowledge of chemistry and engines. Don't be afraid to admit that you don't know all the details.

Talk to me about EGR.

"EGR stands for 'Exhaust Gas Recirculation.' It is a strategy for reducing the temperature in the combustion chamber by diverting some exhaust gas back into the intake manifold. The already-burned gas is cooler, and absorbs heat from the new combustion event, which helps reduce NOx emissions. More NOx is produced when the peak cylinder temperature is higher. It turns out that engine pumping losses can also be reduced by using EGR. Because part of the charge is inert, the throttle can be opened more to admit fresh air. The closer you can operate to wide-open throttle, the better for pumping losses and fuel efficiency. Years ago, the amount of EGR was controlled by a valve that opened and closed in response to manifold vacuum. Another development was valve control based on a backpressure sensor. But nowadays, with most engines having cam phasing, most EGR is internal EGR generated from exhaust and intake valve overlap."

Well. As questions go, this doesn't give you much to go on. The good news is that such an open-ended question leaves you free to design a great answer. Start from the 50,000 foot view and then move down into some of the details, but don't get lost in the weeds. You will want to tell the interviewer what, why and how, as concisely as possible.

Tell me your understanding of how an oxygen sensor works and its function in an emissions control system.

"I don't claim to be an expert on oxygen sensors, but I do remember reading about them in my Internal Combustion Fundamentals course. There are two main types of oxygen sensors: the switching sensor, which was the first one used widely in production, and the linear sensor. If you think we have time, I can describe both, but I'll start with the switching sensor.The switching-type sensor is basically a Galvanic cell with a solid electrolyte, usually zirconia doped with yttria. It is structured to have one side in contact with exhaust gas, and another side, sealed from exhaust, which is in contact with the ambient air. When the sensor is hot enough to conduct electricity, the CO, HCs and hydrogen (if any) on the exhaust side adsorb on the exhaust-side electrode and create a demand for oxygen ions, which are supplied at the air reference side. This sets up a voltage that is dependent on the air/fuel ratio through the Nernst equation. The voltage is low when there is an excess of oxygen on the exhaust side, which we call 'lean,' and is high when there is not enough oxygen, which we call 'rich.' The relationship between air/fuel ratio and the voltage developed by the sensor is highly non-linear. The slope is very steep near stoichiometry, and very shallow at the rich and lean ends of the curve. This is why it is called a switching sensor, and it is mostly used to identify whether the exhaust environment is rich or lean, without trying to identify how much rich or lean. There are a lot of competing demands on the fuel control system. But for the purposes of this discussion, we can focus on the need for the fuel controls to maintain the air/fuel ratio of the exhaust gas near stoichiometry, which allows the catalytic converter to operate at high efficiency. The fuel control system uses the sensor voltage, which has been identified as either rich or lean, to make a decision to increase the amount of fuel injected (if it is lean) or decrease it (if the air/fuel ratio is rich). Obviously, the control system is more complicated than that - it makes an immediate proportional response, but it will have short and long-term adaptive terms that are learned over time if the signal keeps coming back either rich or lean over a period of time. This sensor is positioned just after the confluence of all the exhaust runners, usually near the outlet of the exhaust manifold. Another switching sensor is positioned after the catalytic converter. Would you like me to describe how the rear sensor is used, as well?"

If you already know something about this subject, you could doubtless talk all day about the intricacies of modern fuel control. If this describes you, try to confine yourself to hitting the high points. If you've never heard of an oxygen sensor and you are applying for an automotive emissions control position, your resume goes to the bottom of the pile. Show yourself some respect by educating yourself on at least the basics of the company and function you are applying for.

Describe what engine or vehicle calibration work you have done, and what you found to be the biggest challenges.

"I have calibrated the oxygen sensor heating controls for several applications, including both open loop and closed loop control types. This included all the option selections for whether to use certain specialized functions. Of course the main thing is setting the heater voltage as a function of engine operating conditions and service environment. In the end, oxygen sensor heater control is all about controlling the heater within a small range of desired temperature. That's easiest when you have direct information about the sensor's temperature based on heater resistance or sensor impedance. But you may not have that direct temperature feedback, depending on the application, and the control must be done in open loop based on the operating conditions. That can be a bit of an inexact science involving a lot of empirically determined coefficients. Getting all those coefficients to their best values can be challenging, partly because they can end up interfering with each other. Most oxygen sensors in current use are also sensitive to thermal shock, especially when the engine is first turned on, and you have to find the right balance between that risk and the risk of increased exhaust emissions due to not getting into closed loop fuel control soon enough. It can be challenging calibrating legacy-type controls, which tend to be more empirical in nature, rather than physics model-based. Of course, those controls are constantly being improved, which brings its own challenges - you just get something working, and the next software revision has a new function or a new way of doing the old function and you have to start over. It's worth it though, to know that you took the control idea that was in one person's mind and married it up to the actual hardware and made it all work just like it was supposed to."

If you have engine calibration experience, you likely could talk about it all day long, and would enjoy doing just that! Just hit the high points and let the interviewer drill down deeper into the subject if he sees the need.

Describe generally your understanding of the main components of a gasoline vehicle engine emissions control system.

"While I know that I am not aware of every possible component and strategy that makes up an emission control system in a gasoline engine, I know that generally, the four primary emissions control hardware components are the exhaust oxygen sensor, the catalytic converter, the charcoal canister and the engine control module (ECM). The ECM controls the air/fuel mixture to a desired value, usually right around the stoichiometric ratio for gasoline, based on feedback from the exhaust oxygen sensor. The catalytic converter actually does the bulk of the work in converting carbon monoxide (CO), hydrocarbons (HCs) and various nitrogen oxides (NOx) into water, carbon dioxide and nitrogen gas. It does this by providing a large surface area for catalyzing these reactions using precious metals like platinum, palladium, and rhodium. The reason maintaining an air/fuel ratio near stoichiometry is so important is that CO and HCs require oxygen for their reactions, so their conversion is most efficient when there is more air than fuel, while NOx is converted better in a rich environment. The best mutual efficiency is near stoichiometry. To be completely transparent, I don't know that much about how a charcoal canister works. I know it is supposed to trap fuel vapor instead of letting it directly out into the atmosphere, but I am not completely aware of the details of what happens next. Obviously, the trapped gasoline vapor has to go somewhere, or it would eventually be released or cause the canister to blow up. So it must get routed to the engine at some point. After all, it's just gasoline, so why not? But I admit that I would have a lot to learn about the evaporative emissions system."

With a job interview, it always comes back to the same thing: prepare for the interview you have been granted. The interviewer has looked into your background enough to think that you are a potential candidate. Offer him/her the same respect by knowing something about the company, the products it offers, and the likely content of the job for which you are applying. The sample answer provided shows that the candidate has broad familiarity with automotive emissions control but doesn't know everything. This is a good enough starting point for a college graduate or a candidate with work experience in a quite different area of engineering.

Draw an octane molecule for me. Here's pen and paper.

"It's been awhile since my last chemistry class. Let's see. I know that it has eight carbon atoms (from the prefix oct- in octane) and I know that every carbon atom has four bonding attachment points. From the '-ane' part of the name, I know that there are no double bonds. I also know that it is a hydrocarbon, so every atom in an octane molecule is either a carbon or a hydrogen atom. So I will draw a chain of 8 carbon atoms, each one with a single bond to the other. That leaves three bonds to fill on the two carbon atoms at the ends of the chain, and two open positions for each of the other carbons. So I will just fill in all the hydrogen atoms - 18 of them, and that's an octane molecule."

Surprise! You've been asked a basic chemistry question. The question is simple. You probably learned the answer in high school, if not at college. But it might be such a surprise that you can't think of the answer for a moment. That's ok. Showing a calm and thoughtful approach to a question is appropriate and appreciated by an interviewer. Think, then write it out if you know it. If you don't, go look it up, since it is the major component in gasoline.

Tell me what vehicle data acquisition methods you are familiar with.

"In my previous job, we always used the XYZ system from ABC. XYZ allowed us to flash software and calibrations into our engine controllers right on the vehicle. We could monitor a large number of software parameters as well as data from thermocouples and other external instrumentation. It allowed data acquisition at different rates that roughly corresponded to the software loop execution rates. We could also record and change calibrations as desired. We could monitor all this data in real time and also record it for later analysis. Things usually went pretty smoothly, although using the system with a new engine controller could sometimes produce a few days of red-faced swearing while we worked out all the interface bugs. I've always been told that XYZ was the best data acquisition system in the world, and it was always adequate for my needs. To be honest, though, I suppose that I don't know for sure that it was the best, since it's the only one I ever used. Certainly, I have no problem learning another data acquisition system if your company uses a different one. I feel that my experience with XYZ would make it easier for me to get up to speed on another type of system."

There's no wrong answer to this question. No matter what kind of technical job you are applying for, though, it would pay to spend a few minutes organizing your thoughts for an answer to this very common question. You might try outlining what you are familiar with, including its benefits and limitations, along with expressing your willingness to learn about other systems.

Can you describe for me what happens in a full cycle of a four-stroke internal combustion engine?

"In a four-stroke engine cycle, the crankshaft makes two revolutions for every complete combustion cycle. First is the intake stroke. The intake valves open and the piston moves down, creating a vacuum that draws the air and fuel mixture into the cylinder. There may be some overlap with the exhaust valves being open, but let's stick to the basics of your question. Next is the compression stroke. The intake valves close, and the piston moves up, compressing and heating the air/fuel mixture. Somewhere around top dead center of the piston's travel, the spark will occur. It might be a little bit before or a little bit after, depending on the operating conditions. The resulting 'explosion' in the cylinder will force the piston down, making the crankshaft rotate and producing useful power. Finally, on the exhaust stroke, the exhaust valves open, and the piston moves up, forcing the spent fuel and air out and down the tail pipe."

Once you know that an interviewer might ask you to draw an octane molecule to test your technical mettle, you should realize that no reasonably relevant question is off limits, no matter how basic it might seem. And after all, is asking about the basics of how an engine works irrelevant to emissions control? Most certainly not. If you haven't already, go read about this. Then, remember: 'Suck, Squeeze, Bang, Blow.' Those are the parts of a four-stroke engine's cycle.

Automotive Emission Systems Engineer Interview Questions

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1. It says here on your resume that you are familiar with Matlab. That is an important tool that we use in engine management systems work at ABC Corporation. In your view, what's the best thing about Matlab?
2. When you have a choice between walking over to a colleague's desk, phoning, emailing or instant messaging to communicate with them, which would you choose and why?
3. If you were interviewing someone for this job, what one question would you be sure to ask them?
4. Earlier, I asked you to describe how an oxygen sensor works. Your answer was not correct. How would you go about remedying this lack of knowledge?
5. What do you need from your boss in a work setting, and what do you expect from your peers?
6. I see from your resume that you were part of the on-board diagnostics team at XYZ Corporation. What method of diagnosing a stuck-closed charcoal canister did you provide to our mutual customer, ABC Corporation?
7. What experience do you have working with international suppliers?
8. I see here that you graduated 10 years ago with a Bachelor of Science in Mechanical Engineering, and that you have been employed at one company since then. What has been your approach to staying current on technical developments in your field?
9. You speak English very well. I just hear a slight accent. Where are your parents from?
10. Tell me about any experience you have with on-board diagnostics.
11. Are you more interested in hands-on work like calibration and testing, or more software-related work such as creating controls algorithms and software?
12. Are you able to travel when needed? As the job description says, up to ten percent of your time may involve travel, and it may be for several weeks at a time in remote areas. Would that work for you?
13. What experience do you have writing requirements for hardware or software components? How do you approach it?
14. What part of your previous job did you like best?
15. Are you more interested in theoretical research or applied research?
16. What made you decide to leave ABC Corporation?
17. A friend of yours loves old cars and race cars. He tells you that he has read some articles that say that when you consider every part of the lifecycle of the electric vehicle, it worse than an internal combustion engine vehicle. What do you say to him?
18. What formal problem-solving and process improvement methods do you use?
19. A customer is complaining about an engine stalling problem. Two engine management system solutions have been identified. One requires a change in your area of responsibility. The other would require a change in another subsystem. What should you do?
20. You are testing some new engine control software on a vehicle. You are ten miles from anywhere and the car quits running. Now what?
21. Your customer has asked for a specific software change that you do not believe will solve the very real problem that they are experiencing. What do you do?
22. Tell me about a time when you did a car or home repair. What was it, how did you proceed, and how did it turn out?
23. What would be some of the considerations an engineer would need to take into account in managing fuel and emissions control for CNG as a fuel instead of gasoline?
24. Talk to me about EGR.
25. Tell me your understanding of how an oxygen sensor works and its function in an emissions control system.
26. Describe what engine or vehicle calibration work you have done, and what you found to be the biggest challenges.
27. Describe generally your understanding of the main components of a gasoline vehicle engine emissions control system.
28. Draw an octane molecule for me. Here's pen and paper.
29. Tell me what vehicle data acquisition methods you are familiar with.
30. Can you describe for me what happens in a full cycle of a four-stroke internal combustion engine?

Automotive Emission Systems Engineer Interview Questions

1. It says here on your resume that you are familiar with Matlab. That is an important tool that we use in engine management systems work at ABC Corporation. In your view, what's the best thing about Matlab?

2. When you have a choice between walking over to a colleague's desk, phoning, emailing or instant messaging to communicate with them, which would you choose and why?

3. If you were interviewing someone for this job, what one question would you be sure to ask them?

4. Earlier, I asked you to describe how an oxygen sensor works. Your answer was not correct. How would you go about remedying this lack of knowledge?

5. What do you need from your boss in a work setting, and what do you expect from your peers?

6. I see from your resume that you were part of the on-board diagnostics team at XYZ Corporation. What method of diagnosing a stuck-closed charcoal canister did you provide to our mutual customer, ABC Corporation?

7. What experience do you have working with international suppliers?

8. I see here that you graduated 10 years ago with a Bachelor of Science in Mechanical Engineering, and that you have been employed at one company since then. What has been your approach to staying current on technical developments in your field?

9. You speak English very well. I just hear a slight accent. Where are your parents from?

10. Tell me about any experience you have with on-board diagnostics.

11. Are you more interested in hands-on work like calibration and testing, or more software-related work such as creating controls algorithms and software?

12. Are you able to travel when needed? As the job description says, up to ten percent of your time may involve travel, and it may be for several weeks at a time in remote areas. Would that work for you?

13. What experience do you have writing requirements for hardware or software components? How do you approach it?

14. What part of your previous job did you like best?

15. Are you more interested in theoretical research or applied research?

16. What made you decide to leave ABC Corporation?

17. A friend of yours loves old cars and race cars. He tells you that he has read some articles that say that when you consider every part of the lifecycle of the electric vehicle, it worse than an internal combustion engine vehicle. What do you say to him?

18. What formal problem-solving and process improvement methods do you use?

19. A customer is complaining about an engine stalling problem. Two engine management system solutions have been identified. One requires a change in your area of responsibility. The other would require a change in another subsystem. What should you do?

20. You are testing some new engine control software on a vehicle. You are ten miles from anywhere and the car quits running. Now what?

21. Your customer has asked for a specific software change that you do not believe will solve the very real problem that they are experiencing. What do you do?

22. Tell me about a time when you did a car or home repair. What was it, how did you proceed, and how did it turn out?

23. What would be some of the considerations an engineer would need to take into account in managing fuel and emissions control for CNG as a fuel instead of gasoline?

24. Talk to me about EGR.

25. Tell me your understanding of how an oxygen sensor works and its function in an emissions control system.

26. Describe what engine or vehicle calibration work you have done, and what you found to be the biggest challenges.

27. Describe generally your understanding of the main components of a gasoline vehicle engine emissions control system.

28. Draw an octane molecule for me. Here's pen and paper.

29. Tell me what vehicle data acquisition methods you are familiar with.

30. Can you describe for me what happens in a full cycle of a four-stroke internal combustion engine?