Technical description
Flame lockout
What causes this fault?
This fault occurs when the boiler attempts to start up but cannot successfully establish or detect a steady flame. The most common reasons are a temporary interruption in the gas supply, a build-up of carbon on the ignition parts, or a component failure that prevents the spark from firing.
This issue can occur in freezing temperatures if the external gas regulator or pipework becomes restricted by extreme cold, though it is often a year-round mechanical fault.
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.