High Lockout
F1 on Glow-worm Ci Range

Your boiler is trying to start up but cannot detect a flame, causing the system to shut down for safety.

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

FAULT: THE BURNER LIGHTS BUT THEN GOES OUT. THERE IS NO FLAME DETECTED.

What causes this fault?

This fault occurs when the boiler's internal computer cannot verify that a flame has successfully ignited, leading it to shut down the gas supply for safety. The most common reasons are a worn-out flame sensor that can no longer 'see' the fire, a faulty ignition lead, or a blockage in the gas valve preventing the burner from staying lit.

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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