BoilerFaultCodesYour boiler has shut down because it thinks it detected a flame when there shouldn't be one, or the flame signal is being misread.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Safety switch-off – fault in flame detection
What causes this fault?
This fault occurs when the boiler's internal computer senses a flame signal at a time when the burner should be switched off. The most common reason is that the flame sensing component is covered in carbon deposits or the main gas valve is leaking and allowing a small amount of gas to burn when it shouldn't. In some cases, an electrical fault on the control board can cause it to 'see' a flame that isn't actually there.
This fault is more common during the winter months when the boiler is working harder, as increased usage can lead to a quicker buildup of debris on the sensing electrodes.
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 F.27 — no call-out fees, no surprises.
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