Boiler does not ignite, display shows E01 shortly after a heating or hot water demand.

Safety first: Turn off electrical power to the boiler and close the gas isolation valve before removing any covers. If you ever smell gas, stop immediately and contact your gas supplier or a licensed technician.

• Reset the boiler: Press the reset button as per the Alpha boiler user manual and observe if the boiler ignites normally. If E01 returns, continue.
• Check gas supply: Ensure the gas isolation valve under the boiler is fully open. Confirm other gas appliances in the property work correctly.
• Inspect the flue terminal: From outside, make sure the flue outlet is not blocked by debris, snow, or vegetation, which can affect combustion.
• Check ignition electrode and lead (qualified person only): Remove the combustion chamber cover, inspect the ignition electrode for cracks, heavy carbon deposits, or damage. Clean gently with fine emery paper and ensure the ignition lead is firmly connected at both ends.
• Check flame sensor (ionisation probe): Clean the probe tip carefully and ensure it is correctly positioned in the burner flame path.
• Gas valve operation (qualified person only): Verify the gas valve connector is secure. If there is no gas flow during ignition despite correct voltage, the gas valve may be faulty and should be replaced by a certified technician.

If E01 persists after basic checks, do not continue to operate the boiler. Contact an Alpha-approved service engineer.