Furnace does not start; display shows E01 immediately after a call for heat.

Safety first: Turn off power to the furnace at the breaker and close the gas shutoff valve before touching any internal components. If you ever smell gas, ventilate the area and contact a qualified technician or gas supplier immediately.

Step-by-step checks:

• Verify gas supply: Ensure the main gas cock to the Kospel furnace is open. Check that other gas appliances in the home work normally. If not, contact your gas provider.
• Inspect ignition electrode: Remove the burner access panel. Locate the ignition electrode/igniter near the main burner. Check for cracks, heavy soot, or damage. Clean light deposits with fine emery cloth and a soft brush. Ensure the ceramic insulator is intact and the electrode gap and position match the Kospel service manual.
• Check flame sensor (ionization rod): On many Kospel furnaces, the flame sensor is integrated with or next to the igniter. Remove the sensor rod and gently clean it with fine steel wool or emery cloth to remove oxidation. Reinstall firmly and ensure the wire connection is tight.
• Inspect wiring: Check the harness from the main control board to the gas valve and ignition module for loose plugs, corrosion, or damaged insulation. Reseat connectors.
• Restore power and test: Open the gas valve, restore power, and call for heat. Observe ignition through the sight glass. If the burner lights but the code returns, the flame sensing circuit or control board may be faulty.

When to stop: If you are not trained to work on gas valves or combustion systems, do not attempt to adjust gas pressure or replace the gas valve yourself. Contact an authorized Kospel service technician.