Coleman Furnace Rapid Amber Flash (CP9C Echelon Modulating)
WarningShown as: Amber LED flashing rapidly
Low flame sense current. The control can barely detect the burner flame.
Manual wording: “Rapid Amber Flash - Low flame sense current. Check for dirty or mislocated flame sensor rod.”
Documented for: CP9C Echelon modulating furnaces
Likely causes, most common first
- Dirty flame sensor rod
- Mislocated flame sensor rod
What you can safely check yourself
- Replace a dirty air filter
- Check the outside vent and intake pipes for blockage
When to call a technician
Cleaning or repositioning the flame sensor is done inside the live burner compartment. Call a technician before this turns into a no-heat lockout.
A Coleman furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Installation Manual - Residential Gas Furnace with ECM Motor, Models TP9C*C, YP9C*C, CP9C*C, LP9C*C (Up to 98% Modulating Multi-position), 681292-UIM-B-1211 (Johnson Controls Unitary Products (Coleman), CP9C*C Coleman Echelon modulating gas furnace (manual also covers the identical TP9C, YP9C and LP9C chassis)) · checked 2026-08-25