BoilerFaultCodes F.366 Emergency
Boiler Fault Code F.366
Also written as F366 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F.366 appears across 1 boiler brand and 4 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 safety issue with the gas control valve, meaning it cannot properly shut off the fuel supply, and it has locked out to keep your home safe. (As reported on Viessmann Vitodens 222-F B2TF)
Pick your boiler brand for the F.366 fix
Source
Information for the F.366 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