BoilerFaultCodesAriston 5 P1 Fault Code
Also written as 5P1 — same fault.
The Ariston 5 P1 fault code means: your boiler has failed to light the flame on the first attempt, which usually happens because there is an issue with the gas supply or the ignition system.. It appears on 13 Ariston models in our database.
Technical description: 1st ignition attempt unsuccessful
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Ariston models that show the 5 P1 fault code
Click a model for the full fault code list and model-specific repair notes.
- Challenger 80E Repair: £120-250
- 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
- E-Combi Evo Repair: £120-250
- E-Combi One Repair: £120-250
- E-Combi One 24 Repair: £100-280
- E-Combi One 30 Repair: £120-250
- Egis Repair: £120-250
- Microsystem 15 Repair: £120-250
Source
Ariston 5 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