BoilerFaultCodesYour boiler has failed to light the flame, which means it cannot provide any heating or hot water until the issue is resolved.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Burner in fault position. No flame signal is present. Check the ignition (ignition electrode, lead, ignition module) and the gas supply (gas pressure and gas train).
What causes this fault?
This fault occurs when the boiler's control system attempts to start the burner but cannot detect a flame after several attempts. The most common reasons are a lack of gas reaching the unit, worn-out spark electrodes that fail to ignite the gas, or a faulty sensor that cannot 'see' the flame even if it has successfully lit.
This fault can occur in very cold weather if the external gas meter regulator freezes or if the condensate pipe is blocked by ice, preventing the burner from firing.
DIY fix possible
Check if other gas appliances in your home, like a hob, are working to confirm your gas supply is active.Ensure your gas meter has credit if you use a prepay meter.Press the Reset button on the boiler control panel once to see if the fault clears.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like F4 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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