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2003 Audi A4 Quattro 90400 miles -- electrical completely shuts down on me


In the past 18 months I have put $6500 into my Audi A4. (Timing belt, replace both sets of brakes, replace steering geer, new battery, replace cam adjuster gasket in mid March 09; replaced the equivalent of spark plugs about 1 year ago) It’s got 90400 miles on it and is from 2003.

Recently it would take me two tries to start it. I’d see the EPC signal flash, but then it would go away and it would start. A week later after driving home on a very hot Friday (94 degrees F if heat plays into this problem), I’m driving thankfully in a pretty quiet neighborhood in San Francisco and the car complete stops on me. Lights out. No check engine warning. No EPC light. Nothing. I try to start it once, twic three times. I call triple A and get it towed to my mechanic. When we arrive at the place, it can start again. My mechanic hooks it up to the “brain”, but because the car is working it’s not telling him what went wrong. It’s an “intermittent” problem.

He guesses that it could be 1 of two things: 1) it could be the “crank sensor” malfunctionning which apparently will shut down the electrical if it thinksthe engine is off or 2) the chip in my key is on the blink so the engine thinks it is being stolen and shuts down.

We decide to put in a new crank sensor for $76 + labor.

I’m driving it around town after work but am afraid to drive it to work over the Bay Bridge. Two days ago the light that looks like a car with a key in it goes on and then off.

Should I …

1) take it to another mechanic (who also may not be able to read it’s brain)

2) trade it in, get a new A4

3) sell it, don’t get another Audi ever b/c they still don’t understand electronics in Europe.

Here is what I like about my Audi: the fold down back seats, the size, the quattro, the 5 star safety ratings. But I hate the electrical system. Can I ever trust Audi again?

  1. Yes. Find a mechanic that specializes in german cars. They’ll have the proper diagnostic tools to scan all the “brains” in the car (yes, there’s more than one).
  2. Yes. A viable option. Audi has publicly stated that they’re making an effort to improve reliability. The fact that they’ve admitted defeat says something. Expect the newer models to be better.
  3. Yes. If you feel the need. However, the Europeans understand the benefits of electronics in cars more than anyone (partly to blame for the lack of reliability). German cars have always had the most advanced electronics in cars. Building a car with “unproven” technology obviously has the potential to backfire.

As for the issue at hand: I don’t think the crank sensor nor the key is the problem. For one, the EPC light is completely unrelated to the function of the engine. For two, a bad crank sensor will not shut down the entire electrical system. For three, a bad key will illuminate the “immobilizer” light in the instrument cluster (different from the EPC light). You seem to have a systemic problem that is likely originating in the CAN-BUS (perhaps a bad instrument cluster where the electronics for the CAN gateway are found). If your mechanic doesn’t know what this means, it’s time to find a new one.

Good Luck!

I don’t believe a bad crank sensor will shut the electrical system down. It may stop the ignition system but not the lights. The trouble may be with the ignition switch or something in the wiring before it. Finding the common power path to the lights that were effected should lead to the trouble area.

If you can afford a new car it may be a good time to look at one though you should be able to fix this one without too much trouble and money. There are very good deals being made on new cars now though.

Thanks for both of these comments. They are very helpful.

You’re welcome. Keep us posted on the progress if you can, using the same thread here.

You’re welcome. Keep us posted on the progress if you can, using the same thread here.

Hi all,
Sonnen Audi in San Rafael fixed my car. It took them 2 mins to diagnose it b/c they had the right software to do so. I thought my mechanic did, but apparently he doesn’t. So that was a key learning for me. The problem was the Engine Coolant something. ECT. It was broken/malfunctioning and apparently thought my engine needed gas (when it didn’t) and flooded it. Deep in my files I had a letter from Audi saying that if this malfucntionned, they would cover the cost of replacing it. I also had a weak chip in one of my keys which was setting of the alarm signals. And they agreed that the crank sensor might have also contributed to the problem. So $200 bucks later, I’m driving my car again.
I also learned that they’ve really addressed lots of the issues the 2003 Audis had – rehauled the engine, rehauled the electrical etc. So had this car been kaput, I was teed up to buy a new A4.
Faith in Audi restored. THANKS!

It seems you are singing that song, again, “On the road again. Yes, I’m on the road, again, etc.”