I'm currently experiencing two issues with my A4 Avant B6, manufactured in October 2004.
'Firstly, the warning message 'Rear door open' is displayed on the dashboard, even though the door is properly closed. I haven't been able to locate any warning device.' Perhaps someone has a tip.
On the other hand, the electric lumbar support function is not working in both front seats. Since it happened on both sides simultaneously, I suspect a blown fuse or something similar. However, all the fuses that could potentially be related to this function in the fuse box appear to be intact. Is there perhaps a second fuse box for the comfort electronics? Fuse box?
The contact switch (microswitch) is located in the tailgate lock.
Okay, let's remove the trim and take out the lock. Then you can try bridging the switch and check if the FIS (Front Information System) displays "Lid closed" before you order a new lock.
The fuse for the lumbar support is located on the 9-relay carrier on the body control module (BCM). The BCM with the fuse is located on the driver's side, under the dashboard, behind a triple relay carrier. I can't tell you whether you need to remove the compartment or if you can reach it like that.