BoilerFaultCodes 1P4 High
Boiler Fault Code 1P4
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 1P4 appears across 2 boiler brands and 8 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 water is not flowing through the heating system as efficiently as it should, so it has stopped working to prevent overheating. (As reported on Ariston E-System ONE)
Pick your boiler brand for the 1P4 fix
Source
Information for the 1P4 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