BoilerFaultCodes H9 High
Boiler Fault Code H9
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code H9 appears across 2 boiler brands and 13 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has sensed that the exhaust gases are getting too hot and has shut down as a safety precaution to prevent internal damage. (As reported on Ideal Mexico HE)
Pick your boiler brand for the H9 fix
Source
Information for the H9 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