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

Safety first: Turn off the boiler at the main switch and close the gas isolation valve. Wait for the unit to cool before removing any covers. If you smell gas, do not attempt repair—ventilate the area and contact your gas supplier and a certified technician immediately.

• Reset the boiler: Use the front control panel reset function (refer to your Atlantic model manual). If E01 clears and does not return, it may have been a temporary fault.
• Check gas supply: Ensure the gas isolation valve to the boiler is fully open. Confirm other gas appliances in the home work correctly. If not, contact your gas provider.
• Inspect flue terminal: From outside, make sure the flue outlet is not blocked by debris, snow, or nests, which can affect combustion.
• Check ignition cable and electrode (visual only): With power off and front cover removed (only if you are competent and local regulations allow), look for cracked porcelain on the ignition electrode, loose ignition cable, or signs of burning. Do not adjust gas components yourself.
• When to call a technician: If E01 persists after a reset and basic checks, a certified technician should test the ignition electrode, flame sensor, gas valve coil, and combustion settings using a manometer and flue gas analyzer.