OK, this is what I found about this problem (see picture below).
I specifically insert picture here as I have no idea what they are talking about...
Fault recognition:
- Fault value for gear shift lever position in CAN message gearbox 1 was received.
- Fault value for target gear or engaged gear in CAN message gearbox 1 was received
Rectification:
- Read out error log of engine control unit.
(why ECU ???)
Guided Fault Finding:
- Signal for gear detection
However, this information is from Bosch 5.7 manual and my car has Bosch 5.3
Can anyone comment what the hell all this means and in what direction I should proceed?
A bit more of background: The following 3 control units sit on a dedicated CAN bus and exchange data: 1. ABS control unit 2. Gearbox control unit 3. Instruments panel. One can suggest that it's a connection problem between ABS and Gearbox control units, however, on my 2002 A8 D2 both ABS control unit and Gearbox control unit are located in plenum chamber airtight sealed box (together with Engine control unit). I opened the box and there's are no traces of water ingress and all components are in mint condition, which makes me think CAN bus connection between ABS control unit and Gearbox control unit is tip top.