BoilerFaultCodesViessmann FC Fault Code
The Viessmann FC fault code means: your boiler has detected an internal communication error with the fan that manages airflow, so it has safely shut down to prevent unsafe operation.. It appears on 5 Viessmann models in our database.
Technical description: Burner blocked Electrical fan control (control unit) faulty
What causes the Viessmann FC fault?
This fault occurs when the boiler's control system loses the ability to precisely adjust the amount of gas entering the burner. The most common cause is a failure in the electrical coil that moves the internal gas valve, meaning the boiler can no longer maintain a safe and steady flame to heat your home.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Viessmann models that show the FC fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann FC fault code information on this page is sourced and cross-checked against the official Viessmann service / installation manuals for each affected model.
- Viessmann Vitodens 050-W BPJD manual (PDF)
- Viessmann Vitodens 100-W WB1B manual (PDF)
- Viessmann Vitodens 111-W manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026