BoilerFaultCodes 402 Emergency
Boiler Fault Code 402
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 402 appears across 2 boiler brands 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 safely shut down because it detected that the temperature in the exhaust flue is too high or the safety sensor has tripped. (As reported on Potterton Promax HE Store)
Pick your boiler brand for the 402 fix
Source
Information for the 402 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 31 August 2026