High
F1 on Glow-worm Xtramax HE

Your boiler has tried to light itself several times but has been unable to produce a flame, meaning your heating and hot water will not work.

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.

What the manual says

Manufacturer manual

Ignition fault: The boiler has attempted to light 5 times and failed.

From this model's manual
Verified against the Glow Worm Xtramax He installation & service manual, page 33.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when the boiler's internal computer signals for heat but the burner fails to sustain a flame after multiple attempts. The most common reasons include a lack of gas reaching the unit, a worn-out ignition spark plug, or a sensor that can no longer detect when the fire is lit.

This fault is more common during extreme cold snaps, as external gas meters or pipes can occasionally freeze and restrict the flow of gas to the property.

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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Avoid the next call-out bill

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