Medium
7 11 on Ariston E-Combi One

Your boiler is having trouble 'sensing' the temperature of the water returning from your radiators, which prevents it from heating your home correctly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Return sensor defective (zone 1)

From this model's manual
Verified against the Ariston E Combi One 24 installation & service manual, page 39.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this 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.

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