High Lockout
06 on Glow-worm Ci Range

Your boiler has detected a problem with the sensor that measures the temperature of the water going to your radiators, causing the system to stop working for safety.

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 flow NTC fault

What causes this fault?

This fault occurs when the internal sensor responsible for monitoring the heat of the water leaving the boiler fails or sends an incorrect signal. The most common reason is that the sensor has physically degraded over time or developed an electrical short, meaning the boiler can no longer safely regulate its temperature. In some cases, it may be caused by loose or damaged wiring connecting the sensor to the main control 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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