BoilerFaultCodesYour boiler has tried to light several times but cannot establish a flame, meaning you will have no heating or hot water until it is fixed.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Ignition fault
What causes this fault?
This fault occurs when the boiler's control system attempts to light the burner but fails to detect a stable flame after several attempts. It is often caused by worn-out ignition sparks that can no longer bridge the gap, a faulty gas valve preventing fuel from entering the burner, or a problem with the internal electronics that monitor the flame.
This fault is more common during the first cold snap of autumn when internal components that have been idle over summer fail to operate correctly upon restart.
DIY fix possible
Check if other gas appliances, like a hob, are working to confirm your gas supply is active.If you have a pre-payment meter, check that you have enough credit.Check that your external condensate pipe hasn't frozen if it is very cold outside.Try resetting the boiler by pressing the 'Reset' button (the flame symbol with a cross).
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like F4 — no call-out fees, no surprises.
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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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