BoilerFaultCodesYour boiler is struggling to light the gas to start the heating process, often due to a lack of gas supply or a temporary ignition glitch.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: If the boiler fails to light after five attempts the fault code L1 will be displayed (refer to Fault Code page).
What causes this fault?
This fault occurs when the boiler fails to detect a flame after several attempts to spark, which causes the system to shut down for safety. The most common reasons are a temporary interruption in your gas supply, a build-up of carbon on the ignition parts, or a component failure that prevents the gas from flowing correctly.
This issue can occur in freezing weather if the external gas meter regulator freezes, restricting the flow of gas to the appliance.
DIY fix possible
Check that your gas stop tap is open and you have credit on your meter.Check if other gas appliances in your home, like the hob, are working correctly.Reset the boiler by turning the mode knob to the 'RESET' position and holding for five seconds.
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like L1 — 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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