Control indicates 'Ignition Failure' or similar; burner does not light and unit retries several times before locking out.

Safety first: Shut off power and gas. Wait for the burner area to cool before working near the combustion chamber.

• Listen and observe: On a call for heat, you should hear the inducer fan start (on power-vented models), then the igniter glow or spark, followed by gas valve opening and flame. If you do not hear the inducer or see the igniter glow/spark, focus on those components.
• Inspect the igniter/spark electrode: Remove the burner access panel. Locate the hot surface igniter or spark electrode assembly. Check for cracks, chips, or heavy deposits. Clean light deposits with a soft brush; replace if damaged.
• Check igniter wiring: Ensure the igniter harness is firmly connected to the control module and that wires are not pinched or burned.
• Verify gas valve operation: Confirm the manual gas shutoff is open. If safe and you are qualified, you can listen for the gas valve click during ignition attempts. If the igniter operates but there is no gas sound or flame, the gas valve or gas supply may be at fault.
• Do not repeatedly reset: Repeated ignition attempts can allow unburned gas to accumulate. If ignition fails more than once, stop and ventilate the area, then contact a professional.