BoilerFaultCodesViessmann F2 Fault Code
The Viessmann F2 fault code means: your boiler has shut down because it has detected it is getting too hot, which is usually caused by a lack of water or a circulation problem.. It appears on 9 Viessmann models in our database.
Technical description: Burner in fault position. Temperature limiter has responded. Check the heating system water level, the pump and the lead for the temperature limiter.
What causes the Viessmann F2 fault?
This fault occurs when the boiler's internal sensors detect that the heat exchanger has reached a dangerously high temperature, triggering a safety shutdown to prevent damage. The most common reasons are a failed internal pump that isn't moving water away from the burner quickly enough, or a significant air lock trap in the primary circuit. It can also be caused by a build-up of sludge blocking the flow of water through the narrow passages of the boiler.
This fault is more common in autumn when heating systems are first turned on after summer, as pumps can seize during long periods of inactivity.
DIY fix possible
Check the pressure gauge on your boiler and top up the water if it is below 1.5 barEnsure all your radiator valves are open and not switched offOnce the boiler has cooled down, press the 'Reset' button to see if the fault clears
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Gas Safe Register →Viessmann models that show the F2 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann F2 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