Technical description
Unwanted flame formation
What causes this fault?
This fault occurs when the boiler's internal sensor detects a flame still burning after the heating cycle has finished or before it has even started. The most common reason is a sticking gas valve that isn't closing properly, or a faulty sensor providing a false signal to the 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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