P4 Low

Boiler Fault Code P4

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code P4 appears across 2 boiler brands and 4 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is currently running a routine internal cleaning cycle to fill up its condensation trap and is not actually broken. (As reported on Worcester Bosch Greenstar CDi Compact)

Pick your boiler brand for the P4 fix

Ideal P4 2 models Worcester Bosch P4 2 models

Source

Information for the P4 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 31 August 2026