BoilerFaultCodesAriston 1 04 Fault Code
Also written as 104 — same fault.
The Ariston 1 04 fault code means: your boiler has detected that hot water isn't moving around your system properly, likely due to low water pressure or trapped air, causing the unit to shut down to prevent overheating.. It appears on 16 Ariston models in our database.
Technical description: Insuffi cient circulation
DIY fix possible
Check the pressure gauge on the front of the boiler; if it is below 1 bar, locate the filling loop underneath the unit.Open the filling loop to allow water into the system until the gauge reads between 1.2 and 1.5 bar.Once repressurized, reset the boiler and check if the error clears.
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Ariston models that show the 1 04 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: £150-350
- Clas HE 28 Repair: £150-350
- Clas HE 35 Repair: £150-350
- Clas HE Evo Repair: £120-250
- Clas HE R Repair: £90-250
- Clas Net One Repair: £120-250
- Clas One Repair: £120-250
- Clas System 28 Repair: £120-250
- E-Combi Evo Repair: £80-180
- 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: £120-£350
- Microsystem 15 Repair: £120-250
Source
Ariston 1 04 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