BoilerFaultCodes E00-721 High
Boiler Fault Code E00-721
Also written as E00721 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code E00-721 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 detected a serious internal problem with the gas burner system, causing it to shut down for safety. (As reported on Worcester Bosch 24/28CDi II RSF)
Pick your boiler brand for the E00-721 fix
Source
Information for the E00-721 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