Lack of audio or cell phone functionality may be related to the failure of the audio gateway module.Google+
Car Problem Reports
Mercedes-Benz E320 4MATIC Failed Gateway Module May Cause Lack of Audio/Cell Phone Functionality
Mercedes-Benz E320 4MATIC Problem
Visitor, 2004 Mercedes-Benz E320 4MATIC, 117,000 mi
The radio wouldn't come and I took it to the dealer and the replaced the Tell-Aid module, and ever since
the cruise control segment ring goes counter clockwise, and before the replacement it went clockwise, and
the tell me thats normal. goes from 160 to set speed.