BoilerFaultCodes 302 High
Boiler Fault Code 302
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 302 appears across 1 boiler brand and 5 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 a significant temperature mismatch between its internal sensors, which means it has safely shut itself down to prevent potential overheating. (As reported on Navien NCM 1130HH)
Pick your boiler brand for the 302 fix
Source
Information for the 302 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