Viessmann · Vitodens 200-W B2HB Boiler
The boiler is in control mode but detects a communication error with the Vitotrol remote control unit for heating circuit 3 (which has a mixing valve). This means the remote control cannot properly communicate with the boiler.
Click steps to track your progress.
Check all physical connections and the cable for the Vitotrol remote control for heating circuit 3.
Verify the setting of coding address 'A0' in the 'Heating circuit' group on the boiler control.
Ensure the remote control unit settings are correct.
If the issue persists, the remote control unit may need to be checked or replaced by a professional.