BoilerFaultCodesYour boiler's internal computer has encountered a critical error and can no longer safely control the burner, meaning your heating and hot water will not work.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Burner control unit fault
What causes this fault?
This fault occurs when the boiler's central brain, the burner control unit, suffers an internal communication failure or electrical malfunction. It is often caused by a failing printed circuit board (PCB) or an issue within the ignition system that prevents the unit from safely verifying the flame. Because the boiler can no longer monitor itself accurately, it shuts down as a safety precaution.
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 Fd — no call-out fees, no surprises.
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