Hello everyone,
Having the problem that my Audi S8 D2 facelift goes out during driving, it started with the EPC flashing right at the moment the engine goes out, sometimes the ESP and ABS light turn on ..
But it's gotten worse yet, sometimes the engine just goes out and can start when the car was stopped. A few days ago, it was not so willing to start just after it went out and when I got home, VCDS Do not test the engine right away, it could drive all other points through, but only after 3-4 times it would check the engine.
It's quite periodic but will think it's when the car is running hot it's the worst, but it's also possible to walk in limp mode under test with VCDS (here's the engine turned off)
Has had both engine and gearbox control unit (ECU and TCM) out and look for visible defects with there is nothing to see and there has been no water in the boxes.
Can not really see that the error codes should cause the engine to go out.

I have replaced the fuses in the engine / gearbox control box and cleaned the plug, have all the plug on the engine and cleaned with electronics clean, but nothing has helped
i have order new relay for fuel pump and relay for the ECU.

** Sorry for my bad English


Here are error codes that typically come

Address 03: ABS Brakes Labels: 8D0-907-389.lbl
Part No: 4D0 907 389 E
Component: ABS / ESP allrad D26
Coding: 08397
Shop #: WSC 02314
VCID: 316F639FFBAB8896243-5072

1 Fault Found:
18258 - Powertrain Data Bus
P1850 - 35-10 - Missing Message from ECU - Intermittent

-------------------------------------------------- -----------------------------

Address 17: Instruments Labels: 4D0-919-033-MYX.lbl
Part No: 4D0 919 882 BX
Component: D2-KOMBIINSTR. VDO D26
Coding: 16083
Shop #: WSC 55555
VCID: 871B6D47A5AF66265A7-5072
WAUZZZ4DZYN ***** AUZ7Z0X1071579

3 Faults Found:
01303 - Telephone Transceiver (R36)
49-00 - No Communications
01314 - Engine Control Module
49-10 - No Communications - Intermittent
01327 - Control Module for Parking Aid (J446)
49-00 - No Communications

-------------------------------------------------- -----------------------------
Address 02: Auto Trans Labels: 01L-927-156.lbl
Part No: 4D0 927 156 BN
Component: AG5 01L 4.2L5V RdW 1314
Coding: 00001
Shop #: WSC 02314
VCID: 76E590835245EFAEB11-5072

1 Fault Found:
18258 - Powertrain Data Bus
P1850 - 35-10 - Missing Message from ECU - Intermittent

End ------------------------------------------------- --------------------

 

I would also check the engine wiring harness ground (earth) points. The power to the ECU is experiencing power loss or low power conditions for some reason. The ECU relay you've order could also be the culprit. Let us know how it works out because it sounds like you're on the right path.

 

If the ECU / TCM is dead ? can i get a used one, and replace it or is the immobilizer also build in the ECU / TCM ?
ECU 4D0997558DX
TCM 4D0927156BN

 

Found the error, one of the sockets in boxes where the ECU / TCM is mounted in was defective

 

Excellent. Glad you figured it out.