BoilerFaultCodesAriston 7 11 Fault Code
Also written as 711 — same fault.
The Ariston 7 11 fault code means: your boiler is having trouble 'sensing' the temperature of the water returning from your radiators, which prevents it from heating your home correctly.. It appears on 11 Ariston models in our database.
Technical description: Return sensor defective (zone 1)
What causes the Ariston 7 11 fault?
This fault occurs when the internal computer can no longer read a consistent or accurate signal from the sensor that monitors water returning from your radiators. The most common reason is that the sensor's internal electrical resistance has failed, but it can also be caused by loose or corroded wiring connections inside the boiler.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
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A cover plan would handle faults like 7 11: no call-out fees, no surprise bills.
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Ariston models that show the 7 11 fault code
Click a model for the full fault code list and model-specific repair notes.
- Alteas One Repair: £120-220
- Clas Net One Repair: £120-200
- Clas ONE R Repair: £120-200
- Clas ONE System Repair: £120-220
- E-Combi One Repair: £120-220
- E-Combi One 24 Repair: £90-160
- E-Combi One 30 Repair: £120-220
- E-System ONE Repair: £120-220
- Genus ONE Net Repair: £120-220
- Genus ONE+ WiFi Repair: £120-220
- Microsystem 15 Repair: £120-220
Source
Ariston 7 11 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