BoilerFaultCodesAriston 1 03 Fault Code
Also written as 103 — same fault.
The Ariston 1 03 fault code means: your boiler has detected that water is heating up too quickly because it isn't circulating through the system properly, causing it to shut down for safety.. It appears on 16 Ariston models in our database.
Technical description: Insufficient circulation — gradient Tman >7°C/sec for 3 times
DIY fix possible
Check that your boiler pressure is between 1.0 and 1.5 barEnsure all radiator valves (TRVs) are turned to their highest settingCheck that the isolation valves under the boiler are fully open
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Ariston models that show the 1 03 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 HE R Repair: £100-250
- Clas Net One Repair: £100-£250
- Clas One Repair: £120-250
- Clas System 28 Repair: £120-£250
- E-Combi Evo Repair: £120-£250
- E-Combi One Repair: £120-250
- E-Combi One 24 Repair: £120-250
- E-Combi One 30 Repair: £120-250
- Egis Repair: £120-250
- Genus HE Repair: £100-£350
- Microsystem 15 Repair: £120-250
Source
Ariston 1 03 fault code information on this page is sourced and cross-checked against the official Ariston service / installation manuals for each affected model.
- Ariston Challenger 80E manual (PDF)
- Ariston Clas HE 35 manual (PDF)
- Ariston Clas HE Evo manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026