High Lockout
15 on Glow-worm 30ci Plus

Your boiler is unable to control the gas flow properly, which is preventing it from lighting to provide heating or hot water.

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

Stepper motor fault (gas valve)

What causes this fault?

This fault occurs when the boiler's internal computer is unable to communicate with the mechanical motor that regulates gas flow. The most common reason is that the motor inside the gas valve has seized or failed, but it can also be caused by a loose electrical connection or a fault on 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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Related fault codes

F1View →F4View →F17View →

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