BoilerFaultCodes F64 High
Boiler Fault Code F64
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F64 appears across 2 boiler brands and 17 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler's main internal computer has developed a communication or hardware error and cannot manage the heating process safely. (As reported on Glow-worm Flexicom 18sx)
Pick your boiler brand for the F64 fix
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 27 April 2026