Emergency Lockout
A20 on Potterton Powermax HE

Your boiler is detecting a flame at the wrong time, suggesting that gas might be leaking into the burner when it should be shut off.

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

Technical description

Flame detected during ignition cycle. Check gas valve closes fully. Replace. Check ionisation probe & condensate outlet

What causes this fault?

This fault occurs when the boiler's sensors detect a flame while the gas valve should be closed, or it senses a 'ghost flame' due to an electrical error. The most common reason is a faulty gas valve that is failing to shut off properly, causing gas to linger in the burner. It can also be triggered by a contaminated sensor probe that is sending an incorrect electrical signal to the main control board.

Engineer required

This is a emergency severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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