High Lockout
06 on Glow-worm Xtrafast 96

Your boiler has detected a problem with the internal sensor that monitors the temperature of your heating water, meaning the system cannot run safely.

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 thermistor/wiring fault

What causes this fault?

This fault occurs when the boiler's control board loses communication with the sensor that measures the temperature of the water in your radiators. The most common reason is that the sensor has physically failed or 'drifted' out of its correct electrical range, but it can also be caused by loose or corroded wiring connections between the sensor and the main circuit board.

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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