Furnace locks out shortly after start attempt, display shows E1

Safety first: Turn off the gas supply at the service valve and isolate electrical power before opening the furnace. Risk of gas leak and electric shock.

• Check gas supply: Confirm that the external gas shut-off valve is open and that other gas appliances in the home work. If there is no gas supply, contact your gas provider.
• Inspect ignition electrode: Remove the burner cover and visually inspect the ignition electrode for cracks, heavy deposits, or damage. Clean light deposits with a non-abrasive pad. Ensure the electrode gap and position match the Remeha service manual.
• Check flame sensor (ionisation electrode): Clean the ionisation electrode with fine emery cloth to remove oxidation. Ensure the ceramic insulator is not cracked and the cable connection is tight.
• Gas valve and wiring: Verify that the gas valve connector is firmly seated and that the wiring harness is not damaged. Do not attempt to adjust gas valve settings without proper instruments.
• Reset and test: Restore gas and power, then reset the furnace according to the user manual. If E1 reappears, a technician should test gas pressure, ignition voltage, and replace the gas valve or electrodes if needed.