High Lockout
F19 on Glow-worm Ci Plus

Your boiler has detected that a temperature sensor has become loose or disconnected, preventing it from reading how hot the water is.

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 unclipped (Heating flow)

What causes this fault?

This fault occurs when the temperature sensor responsible for monitoring the water leaving the boiler physically detaches from the pipe or loses its electrical connection. This is often caused by a weakened retaining clip that has popped off, or vibrations over time that have loosened the wiring plug connected to the sensor.

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 →F14View →

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