How much does it cost to fix Keston error code E 31?

Typical repair cost for the Keston E 31 fault is £120-220 including labour.

E 31 High

Keston E 31 Fault Code

Q: What does the Keston E 31 fault code mean?

Your boiler has stopped working because one of its internal temperature sensors is giving a false reading due to an electrical connection issue or a faulty sensor part.

Also written as E31 — same fault.

The Keston E 31 fault code means: your boiler has stopped working because one of its internal temperature sensors is giving a false reading due to an electrical connection issue or a faulty sensor part.. It appears on 3 Keston models in our database.

Technical description: Flow thermistor short circuit - check/replace connections/thermistor

Typical repair cost £120-220 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Keston models that show the E 31 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Keston E 31 fault code information on this page is sourced and cross-checked against the official Keston service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026