Remote Door Lock & AM Radio Antennas
 

The remote door key for my 2003 C230 Coupe can open and close the doors only when the remote is placed close (3 feet) to the driver door. I replaced the key battery but that didn't help. The dealer tried his key and agrees that there must be an antenna problem or something similar. Also, the AM radio seems to have a disconnected antenna. Only strong signals can be received. This problem popped up at the same time as the door problem. Is there a connection between the remote antenna and the AM radio antenna in this model?? Anybody know where the door remote and AM radio antennas are located in this model?

JimC
2003 C230
Audi A4 Avant

Yes, there is a connection. There is a radio antenna amplifier module in the rear roof area.

The key sends a RADIO frequency to the antenna for long distance remote locking, sounds like that is being interrupted.