Ok so some back story I’ve owned 28 Audis everything from multiple b5 S4s to c6 S6 and q5s and q7s and about 6 allroads and everything in between. I used to have a 06 d3 a8 sport that ive always regretted selling in 2018. I just picked up another D3 a8 yesterday to join my two c6 a6s and I’ve been clearing some things up on it with vcds and I have some issues I can’t figure out.

First off the Car button on the mmi and the return button on mmi don’t work whatsoever not even the light is illuminating so I’m not able to adjust air suspension setting nor am I able to access the hidden green menu since the car button doesn’t function. And I’ve read through all the forums on here about cleaning the buttons or replacing the whole panel. This isn’t my first rodeo with old mmi systems. And there is multiple other threads about the car button not functioning and people have cleaned them and or replaced them with other units and still nothing so I’m thinking it’s something deeper causing it not to work so any advice there is appreciated.

Second is the headlights, sometimes the passenger side on will work and sometimes they will both not work and sometimes drivers side. Today just the drivers side low beam was working and the passenger side DRL was only on and no low beam. Also they only work on AUTO setting when you actually change the switch to headlights on they both shut off and then go back to AUTO and they won’t work at all. Makes no sense I’ve never heard these issues with any previous Audis. Fuses are fine. I’m at a loss!

 

Regarding the headlights, I would check the wiring harness as the coating degrades over time. You could have an intermittent short to ground. Easy repair with heat shrink wrap. Can't speak to the AUTO switch symptom but it doesn't hurt to look at the harness around the connectors.

 

The issues you are having a very common separately.

One question though, why would you think they are related?

1. Headlights - I agree a8silver. The jackets used for the wires are of poor quality. I should have taken a picture of the internal wiring when I took it apart. It is weird all the wires in the internal harness disintegrated except for one thin light blue wire that looked pristine.
2. MMI gremlins - is a classic symptom of water/moisture damage

 

As far as the car/return button a new control panel under the buttons fixed that issue! And the headlight issue was just a ballast. Everything is working as it should now

🤘