BoilerFaultCodes 433 High
Boiler Fault Code 433
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 433 appears across 1 boiler brand and 26 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has shut down because it has detected that it is getting far too hot, likely due to water not circulating properly through the system. (As reported on Baxi EcoBlue)
Pick your boiler brand for the 433 fix
Source
Information for the 433 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