BoilerFaultCodes F09 High
Boiler Fault Code F09
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F09 appears across 2 boiler brands and 4 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler's internal pump has stopped circulating water, which prevents your heating and hot water from working to protect the system from overheating. (As reported on Viessmann Vitodens 025-W)
Pick your boiler brand for the F09 fix
Source
Information for the F09 fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026