BoilerFaultCodesAriston 1P4 Fault Code
The Ariston 1P4 fault code means: your boiler has detected that the water pressure is getting low and needs to be topped up to keep running properly.. It appears on 3 Ariston models in our database.
Technical description: Insufficient water — request filling (non-blocking)
DIY fix possible
Locate the filling loop (usually blue levers or a small pull-down tap) underneath the boiler.Slowly open the valve(s) until you hear water entering the system.Watch the pressure gauge on the display until it reaches 1.5 bar, then close the valves completely.
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Ariston models that show the 1P4 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ariston 1P4 fault code information on this page is sourced and cross-checked against the official Ariston service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026