Technical description
Indicates that the burner has failed to light. To reset the boiler turn the selector switch to the reset position.
What causes this fault?
This fault occurs when the boiler's internal sensor fails to detect a flame after several attempts to start. The most common reasons are a lack of gas reaching the burner, a faulty spark that cannot ignite the gas, or a sensor that is too dirty to see the flame that has been lit.
This issue is more frequent during extreme cold spells, as external gas meters or pipes can occasionally freeze and restrict the gas flow required for ignition.
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.