I have a '98 a4 2.8 quattro, and I've noticed a recent problem with the alarm:
When I set it, everything is normal, but after about an hour or so, the anti-theft warning light inside the car stops flashing. The alarm itself isn't triggered or anything, and the doors remain locked, but the lack of warning light flashing would seem to indicate the alarm isn't on. I've searched hi and low on the net and haven't found anyone with the same problem. Does anyone have any experience with or knowledge of this problem? The person I spoke with at the dealership wasn't very helpful. Any help/advice is greatly appreciated. Thanks.

 

You need to interogate the central locking system for fault codes.
In other words, you need a vag com.

 

hey, i kinda have the same problem with my A4 1.8T. all my doors stay locked unless i unlock them from the inside. i can maually lock my drivers door and the red light will flash, but if i dont manually lock a door and someone opens it the alarm with go off. my key fob wont work but the battery is fine. i called the audi dealership where i live and he said that it would cost me $110 just for him to look at it.so if u find any information will you please let me know? cause thats a lot of money for a college student.haha