Furnace displays E01 and will not ignite; often associated with ignition or flame detection problems.

Safety first: Turn off power and gas. Ventilate the area if you smell gas and do not attempt to relight.

• Confirm gas supply: Check that the gas isolation valve to the Sime furnace is open and that other gas appliances function.
• Inspect ignition electrode and cable: Remove the burner cover, check the electrode for cracks or heavy deposits, and ensure the cable is firmly connected at both ends.
• Clean burner: Use a soft brush and vacuum to remove dust and rust from the burner. Do not enlarge burner ports.
• Reset furnace: Restore gas and power, then perform a reset according to the Sime instructions. If E01 reappears, contact a qualified technician for further diagnosis.