Coleman Furnace 10 Red Flashes
Safety faultShown as: Ten red flashes, then a two-second pause, repeating
The gas valve is energized with no call for heat. The main blower and inducer will run and no ignition sequence starts as long as the condition exists.
Manual wording: “10 RED FLASHES: Gas valve energized with no call for heat. The main blower and inducer blower will run and no ignition sequence will be started as long as this condition exists. Check gas valve and gas valve wiring.”
Documented for: TG8S, TGLS, TG9S, TM8X, TMLX, TM9X, TM8T, TM9T, TM8V, TM9V
Likely causes, most common first
- Faulty gas valve
- Gas valve wiring fault
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
The gas valve is being powered when it should not be. Call a licensed technician immediately - do not keep operating the furnace.
A Coleman furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- Installation Manual - Residential Gas Furnace, Models TG9S*MP, GG9S*MP (95.5% AFUE Single Stage Multi-position), 364861-UIM-G-1211 (Johnson Controls Unitary Products (Coleman), TG9S*MP, GG9S*MP 95.5% AFUE single-stage multi-position gas furnaces) · checked 2026-08-25
- Installation Manual - Residential Gas Furnace, Models TG8S*MP, TGLS*MP, GG8S*MP, GGLS*MP (Single Stage Multi-position / Low NOx), 356485-UIM-G-1211 (Johnson Controls Unitary Products (Coleman), TG8S*MP, TGLS*MP, GG8S*MP, GGLS*MP 80% AFUE single-stage gas furnaces) · checked 2026-08-25
- Installation Manual - Residential Gas Furnace, Models TM8X*MP, TMLX*MP (Single Stage Multi-position / Low NOx with High-Efficiency Motors), 437642-UIM-F-1211 (Johnson Controls Unitary Products (Coleman), TM8X*MP, TMLX*MP 80% AFUE single-stage gas furnaces with high-efficiency motors) · checked 2026-08-25
- Installation Manual - Residential Gas Furnace, Models TM9V*MP (Two Stage Variable Speed ECM), 701379-UIM-B-1211 (Johnson Controls Unitary Products (Coleman), TM9V*MP two-stage variable-speed ECM gas furnaces) · checked 2026-08-25