Boiler locks out and displays EA, no ignition, red fault light on, burner does not light.

Safety first: Switch the boiler off at the fused spur and isolate the gas supply if you smell gas. Do not attempt gas work unless you are a qualified Gas Safe engineer.

• Reset the boiler: Press the reset button once and wait for the boiler to complete its ignition sequence. Do not repeatedly reset.
• Check gas supply: Ensure other gas appliances (e.g. hob) work. If not, contact your gas supplier. Make sure the gas isolation valve under the boiler is fully open (handle in line with the pipe).
• Inspect the flue (visually only): From outside, check that the flue terminal is not blocked by leaves, snow, or debris. Do not dismantle the flue yourself.
• Check condensate pipe: In freezing weather, ensure the external condensate pipe is not frozen. If frozen, thaw gently with warm (not boiling) water poured over the external plastic pipe and lag it afterwards.
• If lockout persists: The flame sensor or ignition electrodes may be dirty or faulty, or the gas valve may not be opening correctly. This requires a Gas Safe engineer to test ignition voltage, clean/replace electrodes, check earth continuity, and verify gas valve operation and combustion settings.