BoilerFaultCodesViessmann FA Fault Code
The Viessmann FA fault code means: your boiler has stopped working because the internal fan is spinning too fast during the startup process, preventing the burner from igniting safely.. It appears on 9 Viessmann models in our database.
Technical description: Burner in fault state. Fan speed too high at burner start. Cause: Check the fan, check the fan cables, check the fan control. Press E.
What causes the Viessmann FA fault?
This fault happens when the boiler’s computer detects that the fan is spinning much faster than it should be while trying to light the burner. This usually occurs because the control signals between the fan and the main circuit board are disrupted, or the fan's internal speed sensor has developed a mechanical failure. Without the fan spinning at the precisely correct speed, the boiler cannot safely mix gas and air, so it shuts down as a safety precaution.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Viessmann models that show the FA fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann FA 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 27 April 2026