33 High

Boiler Fault Code 33

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 33 appears across 8 boiler brands and 12 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has lost the ability to accurately measure the temperature of the water flowing through your heating system, so it has shut down as a precaution. (As reported on Ideal Logic Air)

Pick your boiler brand for the 33 fix

Alpha 33 1 model Baxi 33 1 model Ideal 33 1 model Johnson Starley 33 1 model Main 33 2 models Remeha 33 1 model Unical 33 2 models Vokera 33 3 models

Source

Information for the 33 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