BoilerFaultCodesViessmann bd Fault Code
Also written as BD — same fault.
The Viessmann bd fault code means: your boiler has lost connection with the remote control unit that manages your second heating zone, meaning you cannot adjust the temperature for that specific area.. It appears on 1 Viessmann model in our database.
Technical description: Control mode without remote control: Communication fault - Vitotrol remote control heating circuit M2
What causes the Viessmann bd fault?
This fault occurs when the boiler's main control board loses its digital handshake with the remote thermostat managing your second heating zone. Most often, this is caused by a loose connection in the low-voltage wiring or a hardware failure within the Vitotrol unit itself.
DIY fix possible
Check if the Vitotrol remote unit is properly seated on its wall baseSwitch the boiler off at the fused spur, wait 30 seconds, and switch it back on to reset the connectionInspect the remote unit batteries (if applicable) or check for visible damage to the wiring leading to the unit
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Viessmann models that show the bd fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann bd fault code information on this page is sourced and cross-checked against the official Viessmann service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026