I have a Hyundai Sonata 2002 automatic which has just broken down. What happened is that while driving the engine suddenly stopped and the check engine light turned on. I attempted to start the engine but soon after it started it died again. The next time I start it, the engine just cranks but won't start at all. The next day I attempted to start and again the engine started the first time but failed soon afterward. After that it does not start at all. Would appreciate if someone can point me on what might be wrong? I know that an exact diagnosis cant be given but just curious to find out any possible things to look for and estimated costs.

Update some more info I heard from another mechanic: There is no spark and no injector pulse. He believes it could be that the immobiliser is killing the spark. Not sure what that means and would appreciate if someone can give more info on what to expect and estimated costs if the above is true. Another interesting thing is that, occasionally, the engine starts but dies after a few seconds and then won't start at all for long time.

I have also found some info here but cant seem to make much out of the discussion over there. The only thing that I got is that I am having exactly the same issue. This also looks similar to my problem.

Also, this mechanic just wont give me a fault code and one of the other mechanics told me that his computer is incompatible with my car. Moreover he has pointed me to this site and told me to contact them and see if they can help me. I have no clue what to do now and I am not sure why he wants me to contact the company in the link. I will have to wait until Monday to speak to them.

I know I can't fix or diagnose it myself and I think what I am looking for is some advice on what to expect from mechanic, estimated costs and how to deal with him so that I just don't get totally ripped of.

  • Are you sure you have fuel in the tank? Jul 24, 2014 at 18:00
  • yes quite sure as this car has electronic meter showing an estimate of miles it can go before needing a refill. Besides this, its been to the garage and the mechanic must have checked it.
    – Syed Ali
    Jul 24, 2014 at 21:50
  • No worries, just one of those stupid questions you have to ask. I would bet this is fuel related. Probably the I tank fuel pump, but don't know for sure. Jul 24, 2014 at 23:43

3 Answers 3


It sounds like a fuel delivery problem. I suggest getting your fuel pump checked out or replacing it... Usually this is the type of problem that starts out small and eventually gets to the point where you are at right now. Have you noticed recently that the engine seems to have less power at high rpms? Or that maybe it has even started dieing even while you are applying throttle under hard acceleration? Otherwise you may have some other problem...

  • I am not sure of power at high rpm but sometimes I did feel a jerk on initial move after cold start. Any idea about costs?
    – Syed Ali
    Jul 24, 2014 at 14:55
  • Well the jerk really has nothing to do with the fuel pump... That would be more of a transmission thing... When a transmission is cold the fluid doesn't work as well and can result in jerkier movement. But as far as costs go, generally fuel pumps are anywhere from 100$ - $400 depending on vehicle and brand. Jul 24, 2014 at 14:58
  • just had a call from mechanic and he told me that their diagnostic computer came up with an unverified code and that they won't be able to look any further :(
    – Syed Ali
    Jul 24, 2014 at 15:37
  • Unverified code? Haha did they atleast tell you what the code was? Jul 24, 2014 at 15:39
  • Some googling might bring up the result Jul 24, 2014 at 15:39

If the above is true (no spark and no injector pulse), then it could be caused by any combination of the following:

  1. Key Immobilizer faulted (unlikely unless you're using a non-standard key or bypassed it for a remote starter or some crazy electrical nonsense). If it is this, to replace the immobilizer unit and/or keys could be around $300 or so.
  2. Crank Angle / Crank Position / Cam Angle / Cam Position sensor(s). These tell the ECU where the engine is which in turn controls the ignition and injectors. Given that the engine then started, but died again, this is somewhat likely (some will run until warm and die). The sensors themselves are cheap (~$40 or so each), but putting them in will cost you a bit if you can't do it yourself. The difficulty varies wildly based on where the manufacturer decided to locate them on a given engine, and what you have to take off to get to them, but I'd estimate in the neighborhood of $200 - $500.
  3. ECU went bad. Since it then started again and died again, if it were the ECU it would likely be due to overheated components, likely electrolytic capacitors. Estimate: $1,000
  4. Wiring issues / shorts. If something is interfering or shorting with any of the above items (immobilizer, cam/crank sensors, or ECU) then the result will be similar. This can get extremely time consuming to chase down, and thus expensive. Indeterminate amount to fix.

This is operating on the presumption that the information is correct (NO spark + NO injector pulse).

In a broader sense, it sounds like there is a communication breakdown between this shop/mechanic/business. Call AAA or your insurance company and get it towed somewhere that you can trust and will treat you better / communicate with you.


For your vehicle to start you need fuel, ignition, and compression. You can check the ignition easily by holding one of the plug wires, after removing it from the spark plug, a short distance - a quarter of an inch - from the engine block. Have an assistant crank the engine. You should see a strong spark to the block if the ignition is working OK. The fuel side is best checked by having the system connected to a fuel pressure gauge. This is the safest option because of the fire risk inherent with the fuel. Some techs however do disconnect the fuel supply line and aim it into a container, or smother the end of the pipe with a large rag to catch any fuel squirted out whilst the engine is cranked. Gauge pressure, or otherwise will show the fuel is being delivered. Compression can be assumed by checking that the cambelt is in place and rotates with the engine, staying in place and travelling evenly. Electronically your problem could be crankshaft sensor faulty, cam shaft sensor faulty, fuel injector circuit(s), fuel pump relay, fuel pump, faulty fuel gauge(no fuel), ignition system wiring, ignition switch, immobiliser, or even your engines ECU. An obtained fault code would point towards the problem area, and say where the checks should start.

  • thanks, i have update the question and hope it makes sense and probably give more clues.
    – Syed Ali
    Jul 27, 2014 at 0:41
  • Your vehicle needs to be scanned and checked out electronically before doing anything else. Dont be too hard on the garage, if a vehicle is not a main stream or popular model, and they see very few of them in their shop, they are not in a position to carry a full complement of tools. No-one buys expensive kit to sit on a shelf on a 'we might need it' basis. You need to locate a service provider with Hyundai as a main business interest. Jul 27, 2014 at 9:16

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