BoilerFaultCodes P09 Medium
Boiler Fault Code P09
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code P09 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 is struggling to maintain its lowest power setting, which typically indicates a mismatch between the gas pressure and the burner's ability to run efficiently. (As reported on Alpha Pro Tec Plus)
Pick your boiler brand for the P09 fix
Source
Information for the P09 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 7 July 2026