__pena

Hi
My Audi A6 Avant 2012 2.0 TDI won't start randomly and gives me a lot of faults. So sometimes, when I start my car, these faults appear in this order:

Stabilistation program fault! see owners manual
Audi active lane assist: currently unavailable
TPMS tyre pressure: system fault!
Gearbox malfunction: you can continue driving
Parking brake!
Headlight range control: system fault

When I turn off the ignition and wait for a while, the engine starts normally except for a start-stop failure fault. Now when I turn off the engine and turn it on again, all faults are gone and the car works normally for a few days until it does the same again.

I took my car to a dealer, who read the codes and reseted them. They said that they didn't find any faults after resetting and they checked the ABS-sensors which were all fine. I got a print on paper of the faults they read. It was 200 euros for apparently nothing...

Any ideas what could be the problem?

KevinGary

You should post the codes

Anej Kocevar

I have the same problem... how did you solve it?

__pena

An electrical relay was broken in the ECU. When I tried to start the engine with the fault on, I wiggled all the relays in the ECU until the engine started. That's how I found the broken relay. The relay was cheap to change.

Anej Kocevar

Thank you! I will check this with my mechanic. I sure hope this is the problem and not some faulty connection with gearbox compartment. That would be a 2k€+ repair :S

fholm

Search for coolant valve gearbox issues, tons of threads .. This thread is good

Anej Kocevar

We've located relay 645, opened it and found out it was faulty. We repaired it and now everything is back to normal.
Thank you for your help - we would have never figured it out on our own due to misleading errors in VCDS.

Sammy Mahlare

I am currently experiencing almost the same problem
stabilizing malfunction , hill hold assist fault and parking brake fault
it does that after about 20 minutes of drive and it disengage the gear
diagnosing machine showed error U010100 lost communication with TCM
could it be the same relay

Danial

Hi Sammy have you managed to solve the issue?
I have the exact same issue on mine 14 plate A6 and the electrician was blaming battery.. Changed the battery and no luck!
After driving for 30/40 mins this came back
​​​​​​We have tried the Abs wheel sensors and they are still good so I don't know where is the problem

Norrbaggen

Hi Anej.

I have a Audi A6 Avant 2016, is that the same car you have?
I also have all this warnings coming up

-Brake servo restricted
-Headlight range control system fault
-Parking brake fault
-TPMS Tyre pressure system fault
-Stabiliisation control (ESC/ABS): fault

Was all this because of relay 645