I purchased my 2006 A4 about 2 months ago and about half of the time when I start the car the seat belt symbol is lit up and chimes when I have my seatbelt done up and no one is in the passenger seat. The times when it doesn't light up right away when I go over a bump in the road it will chirp at me. Anyone have this happen to them? It is annoying to drive around with the passenger seat belt done up and no one in the seat.

 

Likely have a sensor problem; might want to check under the seat just in case there's a loose connector; 2006 so you might still be under the original 4 year factory warranty - get it checked out under that if possible.

Final option is to use VCDS to change the chime operational mode so it doesn't include the passenger seat (or the driver's seat for that matter )

 

I raised the seat up all the way and had a look, pushed all connectors together. Nothing seemed loose, but I have no idea which is the connection for the seat sensor. Drove across town for hockey last night and no chimming the whole way.

Getting that stupid noise turned off is on my list of things to get done, once I get a VAG-COM or find someone with one.