Looking for help desperately…Two weeks ago I fitted an Apple CarPlay box to my 2016 A8 D4. The CarPlay worked well but I lost my parking aids, reversing camera and sensors. I made the devision to reverse the install but upon completion my won’t start. I’m getting a number of system failures when I try to start the car and the engine won’t even crank. I discovered that the car battery was the original and perhaps past its best after 9 years so I’ve installed a brand new one. Still no change in status. I have a mechanic friend who has attempted to clear the faults but they return straight away. I’ve tested all the fuses I can find and they’re all ok. I’ve even tested the majority of the relays but as again all ok.  Just a couple of multi pin relays I couldn’t test as my test box only goes up to 5 pins. 

The errors I’m seeing are stability control inoperative. TPMS failure, air suspension fault and hill hold not available.

 

Did you code the new battery to the car? It's essential.

I’m getting that done tomorrow am. Just having to charge the battery after draining it by trying to fix the issue over the last few days.

 

Thanks Mark,

What fixes have you attempted which would account for the battery draining?

What make battery did you fit?

Regards,

Gareth. 

I’ve gone through fuses and relays one by one. Made multiple attempts to start the car and tried testing certain circuits with the ignition on. It’s not flat but I got a low battery warning at the end of today so I thought it wise to stick the charger on. Most of the electric circuits work, lights. Radio, air con, windows, soft close , seats etc….

1 hour ago, Buz1500 said:

I’ve gone through fuses and relays one by one. Made multiple attempts to start the car and tried testing certain circuits with the ignition on. It’s not flat but I got a low battery warning at the end of today so I thought it wise to stick the charger on. Most of the electric circuits work, lights. Radio, air con, windows, soft close , seats etc….

Hi sounds like the can gateway has locked everything out, the whole car is programmed to recognise any attempted theft of the vehicle or infotainment system if you fitted anything with the battery connected it probably thinks someone is trying to steal it, can your friend do a factory reset on the system, also as Cliff said the battery coding isa must do.

Steve.

The battery is now fully charged and coded to the car but we still can’t clear the faults or start the car. The errors appear to point to terminal 30 fuse but we can’t locate it. Anyone know?

 

8 hours ago, Buz1500 said:

The battery is now fully charged and coded to the car but we still can’t clear the faults or start the car. The errors appear to point to terminal 30 fuse but we can’t locate it. Anyone know?

 

Youtube.

As an experiment I’ve taken out the 80amp fuse and 651 relay from the engine bay fuse box and tried to start the car. No change, still the same errors but no new ones. With the ignition still on I tested the 80amp fuse location and couldn’t get any signs of power.