BoilerFaultCodesTechnical description
If the boiler does not light after 3 attempts the fault codes L' 'F' will be displayed. Press the reset button (C); the boiler will then repeat its ignition sequence.
What causes this fault?
This fault occurs when the boiler's sensors cannot detect a flame after several attempts to start up. The most common reasons include a lack of gas reaching the unit, a build-up of carbon on the ignition parts, or a component failure that prevents the spark from catching. Essentially, the system shuts down because it cannot confirm it is safely burning fuel to create heat.
This fault is more common during the first cold snap of winter, as gas valves can occasionally stick after being idle over the summer or external gas regulators can be affected by extreme cold.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.