Citan Bluetooth Connectivity Problem Solved

Sounds like a nuisance. Is the error code available? Sometimes those codes point to the Bluetooth module or related software. Before suspecting engine, ignition, or transmission issues, clear the pairing data on both the phone and the Citan, then retry. Also, check for infotainment software revisions. It could be a compatibility issue.

I've cleared the pairing data and re-established the connection without success. If the error code points to the Bluetooth module, could a deeper electrical issue affecting the drivetrain be responsible for the module's malfunction? I want to rule out all possibilities.

While a wider electrical issue is theoretically possible, it's less likely if the engine light isn't on and other systems are working. Given the symptoms, the most probable cause is a fault within the module or its software. If the error code confirms this, I'd suggest a workshop visit for diagnosis and potential module reprogramming or replacement.

Following your advice, I visited a Mercedes technician. The error code confirmed a Bluetooth module configuration issue due to incorrect pairing. The pairing was reset, resolving the issue. The cost was 45€. Thank you for steering me clear of unnecessary engine and transmission investigations.