Boiler Fault Code FAN LOCKOUT

Also written as FANLOCKOUT — same fault.

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

Fault code FAN LOCKOUT appears across 2 boiler brands and 5 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's fan, which safely clears exhaust gases from the unit, has stopped spinning correctly and prevented the system from firing up. (As reported on Potterton Promax FSB 30HE)