F64 High

Boiler Fault Code F64

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code F64 appears across 3 boiler brands and 9 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's internal computer has encountered a serious error and can no longer control the heating system, meaning the unit will need a professional inspection. (As reported on Heatline Monza)

Pick your boiler brand for the F64 fix

Ferroli F64 1 model Glow-worm F64 1 model Heatline F64 7 models

Source

Information for the F64 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