Furnace will not start; inducer motor does not run; LED on control board flashes once repeatedly.

Safety first: Turn off electrical power to the furnace at the service switch and shut off the gas supply before removing panels. If you smell gas continuously, evacuate and contact the gas utility or a licensed technician immediately.

This code on many Fraser‑Johnston/Johnson Controls style boards indicates ignition failure after several attempts.

• Check thermostat call for heat: Set thermostat to HEAT and raise the setpoint. Verify 24 VAC between R and W at the control board.
• Verify gas supply: Ensure the manual gas shutoff valve to the furnace is parallel with the pipe (open). Confirm other gas appliances work. If not, contact your gas supplier.
• Inspect hot surface ignitor: Remove the burner access panel. Locate the hot surface ignitor on the burner assembly. Look for cracks or white spots. If cracked or not glowing during a call for heat, it likely needs replacement.
• Check flame sensor: Locate the flame sensor rod near the burner. Remove the mounting screw and gently clean the rod with fine steel wool or emery cloth. Reinstall and ensure the wire connection is tight.
• Observe ignition sequence (if safe): Restore power and gas, then watch through the sight glass: inducer should start, ignitor should glow, gas valve should click, and burners should light. If ignitor glows but burners never light, suspect gas valve or gas supply. If burners light but shut off within a few seconds, suspect dirty or failed flame sensor.
• If multiple lockouts continue: Turn power off for 30 seconds to reset the board. If the 1‑flash code returns repeatedly, the IFC board or gas valve may be defective and should be tested and replaced by a qualified technician.