BoilerFaultCodesAriston 1p1 Fault Code
Also written as 1P1 — same fault.
The Ariston 1p1 fault code means: your boiler has detected that water is not circulating properly, which is causing it to stop to prevent overheating.. It appears on 1 Ariston model in our database.
Technical description: All Boilers
DIY fix possible
Check that your boiler pressure is between 1 and 1.5 bar on the gauge.Ensure all radiator valves and isolation valves under the boiler are fully open.Bleed your radiators to remove any trapped air that might be blocking water flow.Reset the boiler using the 'Reset' button on the front panel.
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Gas Safe Register →Ariston models that show the 1p1 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ariston 1p1 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 27 April 2026