Boiler Fault Code 00.

Also written as 00 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026

Fault code 00. appears across 2 boiler brands and 7 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 signal suggesting a flame exists when it is actually turned off, which is a safety concern that prevents it from starting to avoid a potential gas buildup. (As reported on Saunier Duval Ecosy)