Medium Lockout
29 on Potterton Performa 24 Eco HE

Your boiler has detected a problem with the sensor that monitors the temperature of the water flowing through your radiators, which prevents the heating from running correctly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description

Fault on Central Heating Sensor

What causes this fault?

This fault occurs when the internal sensor responsible for tracking the temperature of your heating water becomes faulty or loses its connection. The most common reason is that the electrical resistance inside the sensor has drifted out of its normal range due to age or internal wear, meaning it can no longer send an accurate signal to the boiler's control board.

This fault is often noticed during the first cold spell of autumn when the heating system is switched back on after being idle all summer.

Engineer required

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

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