Furnace will not start; LED shows 1 flash repeating; inducer motor does not run.

Safety first: Turn off power at the furnace switch and shut off gas at the gas shutoff valve before removing panels. If you smell gas continuously, evacuate and call the gas utility or a licensed technician.

Steps:

• Verify thermostat call for heat: Set thermostat to HEAT and raise the setpoint 5°F above room temperature. Confirm 24 VAC between R and W at the control board.
• Check gas supply: Ensure the manual gas shutoff valve to the furnace is parallel with the pipe (open). Confirm other gas appliances work.
• Inspect hot surface ignitor (HSI): Remove burner access panel. Locate the ignitor on the burner assembly. Look for cracks or white spots. If damaged, replace the ignitor with the correct Goodman OEM part. Do not touch the new ignitor element with bare fingers.
• Check flame sensor: Remove the flame sensor rod (usually held by one screw). Lightly clean the rod with fine steel wool or emery cloth until shiny. Reinstall and ensure the wire connection is tight.
• Check gas valve operation: Restore power and gas. Observe the ignition sequence: inducer → ignitor glow → gas valve click → flame. If the ignitor glows but no flame appears and you hear the valve click, the gas valve or gas pressure may be faulty and should be tested by a technician with a manometer.
• Reset lockout: Turn power off to the furnace for 30 seconds, then back on to clear lockout and re-test.

If the furnace still shows 1 flash and will not ignite, contact a qualified HVAC technician for gas pressure and control board diagnostics.