Boiler Fault Code FA 306

Also written as FA306 — same fault.

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

Fault code FA 306 appears across 1 boiler brand and 14 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 flame signal when it should be switched off, which means the safety system has locked out the unit to prevent it from operating until it is checked by a professional. (As reported on Worcester Bosch Greenstar CDi Compact)