BoilerFaultCodes F.323 High
Boiler Fault Code F.323
Also written as F323 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F.323 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 trapped air inside its main water circulation system, which is preventing the pump from moving water effectively to provide heat or hot water. (As reported on Vaillant ecoTEC Plus 836)
Pick your boiler brand for the F.323 fix
Source
Information for the F.323 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