BoilerFaultCodesYour boiler has stopped working and locked itself out because it tried to start but failed to light the flame.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flashing on the display indicates lockout (boiler fails to light).
What causes this fault?
This fault occurs when the boiler's control system attempts to start the combustion process but cannot detect a sustained flame. The most common reasons are a lack of gas reaching the burner, a worn-out ignition spark, or a sensor that is too dirty to 'see' the flame once it has lit.
This fault is slightly more common in winter when high demand on the local gas network can cause pressure drops, or when internal components are strained by the cold start-up.
DIY fix possible
Check that your gas pre-payment meter (if you have one) has credit.Verify that other gas appliances, like a cooker hob, are working correctly.Press the reset button once to see if the boiler restarts.
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 F — 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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