BoilerFaultCodes SUP High
Boiler Fault Code SUP
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code SUP appears across 1 boiler brand and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler's temperature sensor has stopped sending the correct signals, meaning the system doesn't know how hot the water is and has shut down as a precaution. (As reported on Grant Vortex)
Pick your boiler brand for the SUP fix
Source
Information for the SUP 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