Technical description
Go to section 'F'
What causes this fault?
This fault occurs when the boiler's internal computer tries to start the ignition process but stops because it cannot detect a flame or verify that the gas is flowing correctly. The most common reason is an aging electronic component or a sensing probe that has become worn or dirty over time. Because the system cannot guarantee it is safe to stay lit, it prevents the burner from firing entirely to protect your home.
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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