BoilerFaultCodesYour boiler is detecting a flame at the wrong time, suggesting that gas might be leaking into the burner when it should be shut off.
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 fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like A20 — no call-out fees, no surprises.
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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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