High Lockout
36 on Glow-worm EnergySaver Combi

Your boiler has stopped working because a sensor that measures the temperature of the water heading to your radiators is sending an incorrect or broken signal.

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

The heating flow thermistor is too resistant.

What causes this fault?

This fault occurs when the main control board detects a signal from the heating sensor that is outside of its normal operating range. The most common reason is that the internal components of the sensor have degraded over time, causing it to report an impossible temperature, or there is a loose connection in the wiring leading back to the boiler's computer.

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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