BoilerFaultCodes G9 High
Boiler Fault Code G9
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code G9 appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has detected that hot water is escaping through the safety overflow pipe, usually because the system is overheating or a valve has failed. (As reported on Worcester Bosch WR325 RSF)
Pick your boiler brand for the G9 fix
Source
Information for the G9 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 27 April 2026