BoilerFaultCodesYour boiler has failed to ignite after several attempts, meaning it cannot provide heating or hot water.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: ALTERNATING 'L' 'F' GO TO FRAME 85
What causes this fault?
This fault occurs when the boiler's control system senses that a flame has not been established after several attempts to start. The most common reasons include a lack of gas reaching the burner, a faulty spark electrode failing to light the gas, or a sensor that cannot detect the flame even if it has lit.
This fault is more frequent during extreme cold spells, as external gas meters or pipes can freeze, restricting the gas flow required for ignition.
DIY fix possible
Check if your gas supply is active by testing another gas appliance like a hob.Check that the white condensate pipe exiting your home hasn't frozen in cold weather.Press the 'Reset' button on the front of the boiler panel to restart the ignition sequence.
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 LF — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Ideal Esprit HE is discontinued — time for a new one?
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.
Affiliate links — we may earn a commission at no extra cost to you.