BoilerFaultCodesTechnical description
Burner control switches to lockout
What causes this fault?
This fault occurs when the boiler detects a persistent flame signal even after the burner should have switched off, or if the internal electrical checks fail during start-up. The most common reason is a build-up of carbon or moisture on the ionisation probe, which tricks the system into thinking a fire is still burning. In some cases, a fault within the main control board or damaged ignition wiring prevents the boiler from safely managing the combustion process.
This fault can be more frequent in autumn or winter when increased condensation or dampness in the air can affect sensitive electrical components and probes.
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.