High Lockout
F4 on Glow-worm 30ci Plus

Your boiler has tried to light several times but cannot establish a flame, meaning you will have no heating or hot water until it is fixed.

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

Ignition fault

What causes this fault?

This fault occurs when the boiler's control system attempts to light the burner but fails to detect a stable flame after several attempts. It is often caused by worn-out ignition sparks that can no longer bridge the gap, a faulty gas valve preventing fuel from entering the burner, or a problem with the internal electronics that monitor the flame.

This fault is more common during the first cold snap of autumn when internal components that have been idle over summer fail to operate correctly upon restart.

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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