Furnace starts but shuts down; LED status light flashes six times repeatedly.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Safety first: Turn off power and gas before removing burner components. If you are not comfortable working around gas, contact a professional.
Step-by-step checks:
- 1. Clean flame sensor: Remove the flame sensor rod from the burner assembly. Gently clean with fine steel wool until shiny. Reinstall and ensure the sensor is properly positioned in the burner flame.
- 2. Check gas supply and shutoff: Confirm the manual gas valve is fully open. If other gas appliances are weak or not working, contact your gas utility.
- 3. Inspect burners: Remove burners (if accessible) and check for rust, debris, or spider webs in the burner ports or orifices. Clean with a soft brush and compressed air. Do not enlarge orifices.
- 4. Reset furnace: Turn power off for 30 seconds, then back on. Call for heat and observe several cycles. If the furnace repeatedly lights and then loses flame, further diagnosis is needed.
When to call a professional: Persistent flame failures can indicate low gas pressure, a failing gas valve, or a defective ignition control board. A technician should measure gas pressure and combustion and replace faulty Philco components as needed.