Bernhard Wittek

Hi all,

got a weird electronic problem since a few days on my 1999 S4:

Drove out of the garage last saturday, when the engine suddenly died.
Tried to fire it up again several times -> no way! Noticed, that the
yellow "EPC" light on the dashboard didn't come up as usual. So I got
me a cup of coffee and tried again after 15 minutes: Yellow EPC light
came, engine fired up! Drove the car for 30 minutes, no problem!
Returned home into the garage. Thought car and me just had a bad
day....

Last morning things went worse, car didn't start at all. Called the
dealer, who came and pulled the codes. Told me that the power supply
for the ECU temporarily failed. He pulled some plugs, cleaned some
contacts and reconnected them -> Car started - fine business, read out
of the codes showed no more errors. Drove for the rest of the day
without any further problems.

Guess what happened this morning

Maybe I should add that temperatures outside are getting lower now, we
had 5 degrees below zero last night... But its definitely not a
battery problem. Car has 80000 miles on the clock, ECU itself seems to
be OK. Could it really be a bad contact?


cheers
Bernhard


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please replace "nospam" with "bw" to contact me directly

IRL

"Bernhard Wittek" <nospam@infosolutions.de> wrote in message
news:bnlp84$12ol4n$1@ID-53934.news.uni-berlin.de...
> Hi all,
>
> got a weird electronic problem since a few days on my 1999 S4:
>
> Drove out of the garage last saturday, when the engine suddenly died.
> Tried to fire it up again several times -> no way! Noticed, that the
> yellow "EPC" light on the dashboard didn't come up as usual. So I got
> me a cup of coffee and tried again after 15 minutes: Yellow EPC light
> came, engine fired up! Drove the car for 30 minutes, no problem!
> Returned home into the garage. Thought car and me just had a bad
> day....
>
> Last morning things went worse, car didn't start at all. Called the
> dealer, who came and pulled the codes. Told me that the power supply
> for the ECU temporarily failed. He pulled some plugs, cleaned some
> contacts and reconnected them -> Car started - fine business, read out
> of the codes showed no more errors. Drove for the rest of the day
> without any further problems.
>
> Guess what happened this morning
>
> Maybe I should add that temperatures outside are getting lower now, we
> had 5 degrees below zero last night... But its definitely not a
> battery problem. Car has 80000 miles on the clock, ECU itself seems to
> be OK. Could it really be a bad contact?
>

It could be a dry joint on the pcb of the ECU. If it's cold the solder could
contract enough not to bridge the gap, when the temperature rises a little
it expands and contact is made. If it's on the power supply track of the ECU
it would be as if the power to it had failed and therefore the fault code
given.

This is just a pure guess, I know nothing about ECU's but I do know that
electronic circuits can be pesky blighters now and then. In my experience
look for the simple solution first, it's usually the right one. If it fails
again, I would try warming the ECU up a little and then trying again. If it
is still the same then you can probably rule out low temperature in that
area.

FWIW HTH

---
IRL
1989 UK Audi 200 QT Avant, 1B engine, 213,000 glorious miles.


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