Mercedes Viano Microphone Failure

That sounds frustrating. I had a similar problem with my previous BMW 5 series, though it wasn't exactly the same. The Bluetooth kept dropping the connection during calls and the sound quality was terrible. Speech recognition also became unusable. Have you tried resetting the infotainment system? Sometimes that fixes weird glitches.

Thanks for the suggestion. I did try resetting the system a couple of times, but no luck. Still no microphone. When you say 'similar problem,' was it also related to the hands-free calling? What eventually fixed your BMW?

Yes, it was definitely related to the hands-free calling specifically, and impacted the sound quality. After a lot of diagnostics, they determined there was an issue with the Bluetooth module itself. If resetting didn't work, and given the error message, I'd say a trip to the workshop is unavoidable. They'll need to properly diagnose the infotainment system.

Thanks, I appreciate the confirmation. I took it to the workshop. Turns out my suspicion was correct: a defective infotainment system. They replaced it. Cost me 815€. At least the speech recognition and telephony work perfectly again. Annoying, but at least it's resolved.