BoilerFaultCodes E21 + RESET High
Boiler Fault Code E21 + RESET
Also written as E21RESET — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code E21 + RESET 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 has failed to ignite and has locked itself out for safety, meaning you will have no heating or hot water until it is reset or repaired. (As reported on Biasi Inovia 2020)
Pick your boiler brand for the E21 + RESET fix
Source
Information for the E21 + RESET 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