Hello,

I have an A3 2.0TDI (WAUZZZ8P05A099307)I'm having quite the problem with my AirBag system. This has become more of a problem since the car is out of date for it's MOT and is now SORN.

The History of the Fault

The fault started with the AirBag light coming on and off intermittently, this progressed and the light is now permanently on. This has been going on for about 2 years and has been permanently on for the last 10-12 months

What I have tried so far

1. I have checked a few things on the advice of others, the connections under the seats have been checked and the contacts cleaned. No damage was found and the fault did not go away
2. I have taken it to an Audi dealer in the hope that they would be able to diagnose the fault. They first changed the passenger side front AirBag sensor (G284) This did not solve my problem
3. On the advice from the dealer I then acquired a new control unit (the part numbers were identical, 8P0 959 655 D) I fitted the new unit and re-coded the replacement so that the software code matched that of the old one. This did not change the fault. (light still on with the same fault codes)
4. The dealer said they have carried out earth and continuity checks on the wiring to the controller and it all checked out OK

What I have at the moment

The air bag light is currently on. Interrogating the system reveals the following fault codes:

2 Faults Found:
01739 - Crash Sensor for Front Airbag; Pass. Side (G284)
012 - Electrical Fault in Circuit - MIL ON
01738 - Crash Sensor for Front Airbag; Drivers Side (G283)
011 - Open Circuit - MIL ON


The only other anomalies are that the Measurements page on the computer said the rear seat tensioner readings were "too high" These don't seem likely to cause the controller to throw out "front air bag sensor" faults but I thought I'd mention it anyway.

I am at a total loss, hopefully someone has seen something similar before and it's getting mega expensive!!! Please heeeelp!!!!!!

John


The full diagnostic read out is attached in case anything else is relvant

 

Hi.
Are these permanent faults? Meaning if they are erased they come straight back up?
If so then on the basis of your information (ecu replaced and sensor replaced) it has to be a wiring fault. Open circuit can mean sensor internally faulty, ecu internally faulty or the wiring itself. It's irresponsible of the Dealer to advise the ecu needed replacing before diagnosing it fully. It's unusual that both crash sensors are showing faults and "electrical fault in circuit" is usually a sensor fault (try swapping the 2 over?)
Just for your information, the connections under the seats are for the side airbag units, in the seat backrests, not for the crash sensors. The crash sensors incase you aren't aware are located behind the headlights I think

 

Hi, thanks for the info. It is a hard fault, they both come straight back on after a reset.

I'm away with work at the moment but I'll have a look at the wiring when I get back.

I'll also try swapping the sensors and see what that does to the fault codes.

It's there anywhere I could find wiring diagrams that tell me which pins on the ecu connector go to the sensors?