Coleman Furnace 1 Red Flash (CP9C Echelon Modulating)
Safety faultShown as: One red flash, two-second pause, repeating
Flame is present with no power being supplied to the gas valve - gas is reaching the burners when it should not be.
Manual wording: “One Red Flash - Flame is present with no power being supplied to gas valve. This can be caused by a gas valve that is slow to close or that leaks gas through to the burners.”
Documented for: CP9C Echelon modulating furnaces
Likely causes, most common first
- Gas valve slow to close
- Gas valve leaking gas through to the burners
What you can safely check yourself
- If you smell gas, leave the house and call the gas utility from outside
When to call a technician
Call a licensed technician right away. A leaking gas valve is a safety hazard and only a professional can test and replace it.
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