1p4 High

Ariston 1p4 Fault Code

Also written as 1P4 — same fault.

The Ariston 1p4 fault code means: your boiler is struggling to circulate water effectively, which is causing it to shut down to prevent overheating.. It appears on 1 Ariston model 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: Clas Net one CombiClas one CombiClas System one
Typical repair cost £120-£350 (including labour)

DIY fix possible

Check if your radiator valves are fully openEnsure your boiler pressure is between 1.0 and 1.5 barTry resetting the boiler using 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 27 April 2026