Citroen C4 Audio System Failure

A complete audio system failure in your C4 is indeed perplexing. Does the head unit power on? Can you navigate through the menus, change radio stations, or attempt to connect via Bluetooth, even without any actual audio output? If the head unit seems functional, it is possible the amplifier has failed. The amplifier increases the power of the audio signal before it is sent to the speakers. However, complete audio loss from all sources (radio, Bluetooth, etc.) does lean toward a possible amplifier issue. This component could be separate or integrated into the head unit depending on your C4 trim level.

Yes, the head unit turns on, and I can navigate the menus, change radio stations, and even connect via Bluetooth. Still no sound though. Any ideas before I consider taking it to a shop?

Okay, since the head unit operates normally but no audio is present, it strengthens my suspicion of an amplifier problem. Alternatively, although less likely if no sound is present at all, it could indicate a widespread speaker issue, or a problem with the wiring harness connecting the head unit to the speakers. Given the symptoms, and before incurring potentially unnecessary diagnostic costs at a repair shop, it may be advantageous to check if the bass speaker is working. However, I would recommend seeking professional diagnostics to pinpoint the faulty component. The defective bass speaker is likely the cause. Based on experience, such a repair could cost you around 280€.

Thanks for the detailed analysis! The audio failure was indeed due to a defective bass speaker. The repair set me back 280€ as you predicted.