High Lockout
60° neon flashing on Potterton Performa 28i

Your boiler is lighting but cannot detect that the flame has been lit, causing it to shut down shortly after 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

Burner extinguishes after 10 seconds (Flame failure).

What causes this fault?

This fault occurs when the boiler's internal sensors fail to confirm that a flame is present, even if you can see it lighting briefly. The most common reason is a worn-out sensing probe that has become covered in carbon soot or a faulty control board that is no longer 'listening' for the flame signal. For safety, the boiler shuts down immediately because it thinks it is leaking unburnt gas.

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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