High Lockout
E31 on Potterton Powermax HE

Your boiler has detected a problem with the temperature sensor that monitors the water returning from your radiators, preventing the system from operating correctly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Return thermistor error

What causes this fault?

This fault occurs when the internal computer loses communication with the sensor that monitors water temperature coming back from your radiators. The most common reason is that the sensor has physically failed or developed an electrical fault, though it can also be caused by loose or damaged wiring connecting the sensor to the main control board.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

E32View →E28View →E20View →

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