Boiler Fault Code fI-

Also written as FI — same fault.

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

Fault code fI- 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 is performing a routine self-check and safety fill of its condensation system because the power was recently switched off and on. (As reported on Worcester Bosch Greenstar R29 40 HE)