Boiler locks out with EA on display, burner does not ignite, you may hear clicking from the gas valve or ignition but no flame is established.

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

Basic homeowner checks:

• Verify that the gas supply to the property is on (check other gas appliances such as a hob).
• Check the boiler pressure gauge is typically between 1.0–1.5 bar when cold. If low, top up via the filling loop according to the Worcester manual.
• Reset the boiler using the reset button or control knob and observe whether the EA code reappears.
• Ensure the flue terminal outside is not blocked by debris, snow, or vegetation.

If EA persists (for professionals only):

• Inspect the ignition electrode and flame sensor on the burner assembly for cracks, carbon build-up, or incorrect gap; clean with fine emery cloth and refit or replace as needed.
• Check the ignition lead for damage or tracking to earth.
• Measure gas inlet and burner pressure at the Worcester gas valve and compare with manufacturer data; adjust or replace the gas valve if out of spec.
• Verify correct operation of the fan and venturi; ensure the air/gas ratio is correct using a flue gas analyser.

If the boiler repeatedly locks out with EA after basic checks, contact a Gas Safe registered engineer; ignition and gas valve work must not be done by unqualified persons.