I have 2008 S6. Tail lights giving error code but all bulbs fine. What I finally did was to plug and unplug the connector from the light housing multiple times? So here's my rationale. The contacts in both the male and female portions of the connection appear to be aluminum.Probably done for cost then weight. Aluminum corrodes over time BUT visual indicators are benign. By plugging and in unplugging multiple times you scrape off the corrision. NO ERROR CODES NOW. Life is good again.

 

A 4-4ear belated thanks. this was 100% the correct answer for my 2008 A6. took about the time it takes to change a bulb (which i did several times b4 reading this simple solution). Thanks Plimag...

 

I have had the same problem for over 5 years now and I am glad I found this thread. I took apart the light harness today and did not find anything that seemed like a 'ground pin'. Sorry, bit of a novice here. Can someone help? I have attached some pictures here. Can someone tell me where this pin/wire is?

https://ibb.co/jSSk7m
https://ibb.co/bN6OtR
https://ibb.co/fjMdSm

 

I fortunately haven't had this problem (yet) but a friend said he just added a relay and it worked.

 

Done what the guy said to clean it out and it’s working perfect now and that’s with a q3 need to get a new one tho cause it’s so dirty

 

I’ve had similar issue in past on both 03 RS6 and 08 S6. I didn’t “clean” them. I just unplugged and plugged a few times. That seemed to scrape off the light corrosion and re-establish a good connection. Put some dielectric goop in there as well.

 

Yeah that’s it you should see the rods tho it’s like a holes blowed through it what a mess, but yeah man cleaned it up put back together and not a problem since, so thanks again to all yous