BoilerFaultCodes 120FF High
Boiler Fault Code 120FF
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 120FF 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 The code you are seeing refers to the technical heat output rating of your specific boiler model rather than a fault error, though if your boiler has stopped working, it indicates an underlying failure that requires professional diagnosis. (As reported on Glow-worm Glow-worm Micron 100FF 120FF)
Pick your boiler brand for the 120FF fix
Source
Information for the 120FF 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