High Lockout
Neon9 on Potterton Performa System HE

Your boiler has detected that a temperature sensor is not working correctly, meaning it cannot accurately measure how hot the water is.

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

Fault on Temperature Sensor

What causes this fault?

This fault occurs when the boiler's control board loses communication with the internal temperature sensor, often because the component has suffered electrical failure or chemical degradation over time. The most common reason is that the sensor has become 'scaled up' or the internal thermistor has worn out, preventing it from sending a reliable signal to the boiler.

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

Neon 7View →Neon 8View →

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