BoilerFaultCodes FU High
Boiler Fault Code FU
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code FU appears across 1 boiler brand and 15 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 that heat is building up too quickly and cannot circulate around your home, likely due to a blockage or a pump failure. (As reported on Ideal Logic Code Combi ESP1)
Pick your boiler brand for the FU fix
Source
Information for the FU 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 27 April 2026