Boiler Fault Code h 9

Also written as H9 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026

Fault code h 9 appears across 2 boiler brands and 3 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 it is running at a dangerously high temperature and has automatically shut itself down to prevent damage. (As reported on Ideal Mexico)