BoilerFaultCodes P1, P2, P3, P4... High
Boiler Fault Code P1, P2, P3, P4...
Also written as P1P2P3P4 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code P1, P2, P3, P4... appears across 1 boiler brand and 7 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is struggling to start up its internal computer system and may have a blown fuse or a faulty control circuit. (As reported on Worcester Bosch Greenstar i)
Pick your boiler brand for the P1, P2, P3, P4... fix
Source
Information for the P1, P2, P3, 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 27 April 2026