75 High

Boiler Fault Code 75

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 75 appears across 3 boiler brands and 17 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler’s internal flame sensor is dirty and can no longer see the fire, causing the system to shut down for safety. (As reported on Worcester Bosch Greenstar Utility 18/25)

Pick your boiler brand for the 75 fix

Alpha 75 13 models Vokera 75 3 models Worcester Bosch 75 1 model

Source

Information for the 75 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