BoilerFaultCodesAriston 1 P1 Fault Code
Also written as 1P1 — same fault.
The Ariston 1 P1 fault code means: your boiler has detected that water is not moving around your heating system fast enough, triggering a safety shut-off to prevent overheating.. It appears on 14 Ariston models in our database.
Technical description: Insufficient circulation indication
DIY fix possible
Check your boiler pressure gauge and top it up to 1.5 bar using the filling loop if it is below 1 bar.Ensure all radiator thermostatic valves are fully open to allow water to circulate freely.Check that any external heating system filters are not blocked and the central heating pump is audibly running.
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Search the official register for a qualified engineer in your area.
Gas Safe Register →Ariston models that show the 1 P1 fault code
Click a model for the full fault code list and model-specific repair notes.
- Challenger 80E Repair: £100-250
- Clas HE 24 Repair: £120-250
- Clas HE 28 Repair: £120-250
- Clas HE 35 Repair: £120-250
- Clas HE Evo Repair: £120-250
- Clas Net One Repair: £120-250
- Clas One Repair: £120-250
- Clas System 28 Repair: £150-300
- E-Combi Evo Repair: £120-250
- E-Combi One Repair: £100-250
- E-Combi One 24 Repair: £100-£350
- E-Combi One 30 Repair: £100-250
- Egis Repair: £120-250
- Microsystem 15 Repair: £100-250
Source
Ariston 1 P1 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