High Lockout
10 on Glow-worm 30ci Plus

Your boiler has stopped working because a sensor that monitors the temperature of the water returning from your radiators 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 return NTC fault

What causes this fault?

This fault occurs when the sensor responsible for measuring the temperature of the water returning to the boiler begins sending incorrect data or stops communicating entirely. The most common reason is that the internal components of the sensor have degraded over time or the electrical connection has become loose or damaged. Because the boiler can no longer accurately monitor the system temperature, it shuts down as a safety precaution to prevent overheating.

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

F1View →F11View →

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