My 2014 rex started having an issue with the Harman kardon audio system two days ago.
Idrive/headunit all function normally but there is no sound output from any of the speakers. Fm band, Bluetooth connection, parking audio warnings are all not producing any sound. Only the initial startup tone is audible. I removed the rear seat and disconnected/reconnected the HK amplifier but that did not resolve the issue.
Scanning the car with bimmerlink produced one error each on the amp and the headunit:
Amp - b7f4a8 front left bass channel error
Headunit- e1c440 reset
Clearing the errors did not help.
My feeling is that maybe the amplifier has gone out, but I don't know how to test it.
Perhaps the connection from the headunit computer module to the amp needs reseated ?