High Lockout
04 on Glow-worm Xtrafast 96

Your boiler is failing to light the flame needed to heat your water and radiators.

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 -flame detection

What causes this fault?

This fault occurs when the boiler attempts to start up but cannot confirm that a flame has been successfully lit. The most common reasons are that the spark isn't reaching the burner, the sensor that detects the heat is dirty or worn out, or the gas valve isn't opening correctly to provide fuel.

This fault is slightly more common in winter, as cold weather can cause moisture to affect electrical components or lead to fluctuating gas pressures in the external supply lines.

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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