Safety first: Turn off power and gas. Ignition lockouts indicate repeated failed ignition attempts.

Steps to address IGN error:

Clean burners: Remove burner tray and clean burners with a soft brush and compressed air. Clear any rust flakes or debris from ports.
Clean flame sensor: As with FS faults, clean the flame rod with fine abrasive pad and ensure proper positioning.
Check gas supply: Confirm adequate gas pressure and that other appliances are not starving the line when they run.
Observe ignition: After reassembly, watch through the sight glass to ensure smooth ignition and stable flame. If flame lights but drops out quickly, flame sensing or control module issues are likely.
Replace ignition module if needed: If all mechanical and gas issues are resolved and IGN persists, the ignition control module may require replacement.

Note: Frequent lockouts should be investigated promptly to avoid damage to components.

Display shows 'IGN' and heater cycles through ignition attempts without staying lit.

Possible Causes