Your boiler has lit correctly but the flame has gone out unexpectedly, often due to a temporary interruption in the gas supply or a blocked condensate pipe.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flame Loss
What causes this fault?
This fault happens when the boiler successfully starts up, but the flame goes out shortly after because the system can no longer detect it. The most common reasons are a lack of gas entering the unit, a dirty sensor that can't 'see' the flame, or a blockage in the pipe that carries away waste liquid.
This fault is frequently seen during freezing winter spells, as the external condensate pipe can freeze solid and cause the boiler to shut down for safety.
DIY fix possible
Check that your gas meter has credit and the isolation valve is open.Inspect the white plastic pipe (condensate) leading outside for signs of freezing or blockages.Restart the boiler by pressing the 'Reset' button.
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A boiler cover plan would cover faults like Fn — 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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