BoilerFaultCodesAriston 108 Fault Code
The Ariston 108 fault code means: your boiler has detected that the water pressure in your heating system is too low to operate safely, so it has shut down to protect itself.. It appears on 15 Ariston models in our database.
Technical description: Insuffi cient water (request fi lling)
DIY fix possible
Locate the filling loop, which is usually a flexible metal hose with one or two small valves connecting your cold mains pipe to your heating pipework.Open the valve(s) slowly to allow water into the system while watching the pressure gauge on the front of the boiler.Stop filling as soon as the needle reaches the green zone, typically between 1.0 and 1.5 bar, then tightly close the valve(s).
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Ariston models that show the 108 fault code
Click a model for the full fault code list and model-specific repair notes.
- Alteas One Repair: £0-120
- Clas HE 24 Repair: £0-80
- Clas HE 28 Repair: £0-80
- Clas HE 35 Repair: £0-80
- Clas HE Evo Repair: £80-150
- Clas Net One Repair: £80-150
- Clas ONE R Repair: £0-120
- Clas ONE System Repair: £0-120
- E-Combi Evo
- E-Combi One
- E-Combi One 30
- E-System ONE Repair: £0-120
- Genus ONE Net Repair: £0-120
- Genus ONE+ WiFi Repair: £0-120
- Microsystem 15
Source
Ariston 108 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 7 July 2026