BoilerFaultCodesYour boiler thinks it sees a flame before it has even started the ignition process, which is preventing it from running for safety reasons.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flame detection fault (Flame detected before ignition).
What causes this fault?
This fault occurs when the boiler's sensors detect a flame signal at a time when there shouldn't be one, such as during the initial startup checks. The most common reason is a faulty flame sensing electrode that is sending a false signal, or a carbon buildup that is allowing electricity to leak across the sensor. In some cases, the main control board may be malfunctioning and incorrectly interpreting signals from the burner.
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 F16 — no call-out fees, no surprises.
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