High Lockout
E20 on Potterton Gold Combi HE

Your boiler has stopped working because a sensor that monitors the temperature of the water returning to the unit has developed a fault.

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

Central Heating NTC Fault

What causes this fault?

This fault occurs when the boiler's control board loses communication with the sensor that monitors water temperature coming back from your radiators. The most common reason is that the internal components of the sensor have failed due to age or wear, but it can also be caused by loose or damaged electrical wiring. Since the boiler cannot safely monitor how hot the water is, it shuts down as a safety precaution.

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

E50View →E28View →

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