Status LED flashes eight times repeatedly, furnace may start but shuts down quickly
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: Turn off power and gas before servicing. Avoid touching hot components.
Steps to check:
- Clean flame sensor: Remove the flame sensor and clean with fine steel wool. Reinstall so it is fully in the burner flame.
- Check burner ground: Ensure burner rack and manifold screws are tight and making good metal-to-metal contact with the furnace chassis. Clean any rust or paint at grounding points.
- Verify line polarity: At the furnace disconnect (advanced), confirm hot and neutral are correctly wired. Incorrect polarity can reduce flame sensing.
- Observe flame: After restoring power and gas, call for heat and observe the burner flame. It should be steady blue with minimal yellow tips. Weak or lifting flames may indicate low gas pressure.
When to call a professional: If flame remains weak, if you suspect gas pressure issues, or if the code persists after cleaning, have a technician measure flame signal microamps and gas pressure and correct as needed.