Hi. Just found this site, lots of good info.
I have a 1998 A3 which has served me well but recently the stop light (failure) warning light and alarm keeps going off even though all the bulbs are working. Sometimes it goes for days not showing a fault then sometimes just the warning light comes on. Most annoyingly though sometimes the beep alarm will sound every few seconds. Thankfully it does not last too long and does not happen too often.
I have checked all the bulbs thoroughly and replaced all of the high line. I have cleaned all the bulb connections and units and I have also had the brake light switch replaced. All to know avail.
If anyone can suggest any other fixes I would be most grateful.
Sorry this is a long message (I am new to this!)