1P4 High

Ariston 1P4 Fault Code

The Ariston 1P4 fault code means: 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.. It appears on 6 Ariston models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Insufficient circulation indication
Typical repair cost £120-250 (including labour)

DIY fix possible

Check all radiator valves in your home are fully open.Check your boiler pressure gauge; if it is below 1 bar, top it up using the filling loop.Restart the boiler by pressing the reset button.

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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 7 July 2026