BoilerFaultCodes F.023 High
Boiler Fault Code F.023
Also written as F023 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F.023 appears across 1 boiler brand and 3 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 the water leaving it is much hotter than the water returning, suggesting a blockage or a problem with the pump circulating the water efficiently. (As reported on Vaillant ecoTEC plus)
Pick your boiler brand for the F.023 fix
Source
Information for the F.023 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