High Lockout
25 on Potterton Performa System HE

Your boiler has detected that a temperature sensor is not working correctly, which has caused the system to stop running to prevent overheating.

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 Central Heating Sensor

What causes this fault?

This fault occurs when the boiler's control board can no longer read accurate information from the flow temperature sensor. The most common reason is that the internal thermistor has physically failed or developed a short circuit, meaning the boiler can no longer safely monitor how hot the water is getting. In some cases, it may also be caused by loose or damaged wiring connecting the sensor to the main control unit.

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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