Not a fault code Medium

Boiler Fault Code Not a fault code

Also written as NOTAFAULTCODE — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code Not a fault code appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is currently in a manual testing mode used by engineers, which is why it has stopped operating normally. (As reported on Worcester Bosch Greenstar 15i System)

Pick your boiler brand for the Not a fault code fix

Worcester Bosch Not a fault code 1 model

Source

Information for the Not a fault code 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