Technical description
ignition
What causes this fault?
This fault occurs when the boiler's internal computer tries to start the combustion process but cannot confirm that a flame has successfully lit. This is usually caused by a buildup of carbon on the ignition probes or a mechanical failure in the gas valve that prevents fuel from reaching the burner. Without a sustained flame being detected, the system stays in this phase to prevent unburnt gas from building up.
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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