High Lockout
S.03 on Glow-worm Ultracom 2 HXI

Your boiler is currently attempting to light the flame but is failing to do so, meaning you won't have heating or hot water until it succeeds.

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

What causes this fault?

This fault occurs when the boiler tries to light the burner but cannot detect a stable flame after several attempts. The most common reasons are a lack of gas reaching the unit, worn-out spark electrodes that can no longer create a light, or a buildup of debris blocking the ignition process.

This fault is more common during the first cold snap of winter, when increased demand can highlight failing components or issues with gas supply pressure.

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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