BoilerFaultCodes H09 High
Boiler Fault Code H09
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code H09 appears across 1 boiler brand and 2 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 water pump is not sending signals to the control unit, which means the system cannot safely circulate heated water to your radiators or taps. (As reported on Worcester Bosch Greenstar 12i System)
Pick your boiler brand for the H09 fix
Source
Information for the H09 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