Short circuit in control unit due to water ingress, Audi A6 2.5 TDI

Hello,
'I'm having the following problem: My engine control unit (ECU) has a short circuit due to water ingress. I've already taken a look inside, but I can't really see anything. When I turn the ignition on, the ASR warning light in the dashboard stays on constantly, and there's a constant humming noise coming from the fuel injection pump. It also won't start. The diagnostic tool also showed error codes, but none of them could be cleared. Then I got the message: 'No communication possible!' I've already written off the ECU. What happens if I now buy a used ECU with the immobilizer? My key will have to be reprogrammed to the new ECU, right?' What about the mileage on the used control unit? Shouldn't it be adjusted to match the mileage of my instrument panel insert, since these two components communicate with each other? Can an Audi dealership adjust the mileage on a used control unit? I've heard that this can't be done an unlimited number of times. Is that true? It's pointless for me to buy a used item if it doesn't work.

Hi,

If you're just copying it anyway... then try to dry it out. Maybe it will work, especially if it hasn't suffered too much damage from the power surge. You have nothing left to lose.

Disassemble the device, take apart the components, and then place the bare circuit board in the oven. Set the oven to 60 degrees Celsius and leave it like that for 24 hours (of course, this only works with electric ovens... but I think that's obvious!). A few years ago, we had a discussion about this, and it turned out that the time required to effectively remove water absorbed into the circuit board is extremely long.

Water alone doesn't damage electronics; it's the combination of water and electricity that causes problems. Therefore, please don't try to use it anymore; first, dry it out completely. Maybe you'll get lucky.

Best regards,

Jan.

I discovered a hairline crack with a magnifying glass and a black spot on the circuit board. It looks like something blew out.

Does anyone happen to have such a control unit lying around, or do you know someone who might no longer need it and would be willing to sell it ? If so, I would be very grateful.


Audi A6 2.5 TDI, 110 kW, AKN 03/99.
Part Number: 4B0 907 401C
Bosch Part Number: 0281 001 836

Best regards,
Sven

Hi Sven;
My condolences .

I have an Audi V6 TDI engine lying around, but I'm not exactly sure which model it is! I'll have more information over the weekend when I'm back home. To my knowledge, it was originally for a 1999 Audi with an automatic transmission, but it was converted to a manual transmission.

If you are interested, please send me a private message .

Hi again,

Unfortunately, this part is from a Passat, but also from an AKN engine. The part number is 3B1907401B, and the Bosch part number is 0281010447. I'm not sure if it's compatible. It would be worth questioning...


Regards,
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