BoilerFaultCodes 333 High
Boiler Fault Code 333
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 333 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 is temporarily preventing itself from firing up because it cannot detect water moving through the heating system as expected. (As reported on Worcester Bosch Greenstar CDi Compact)
Pick your boiler brand for the 333 fix
Source
Information for the 333 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