Coleman Furnace: 1 Flashes
A Coleman furnace LED pattern starting with 1 flashes matches 4 documented codes: 1 red flash, 1 green flash (CP9C Echelon modulating), 1 amber flash (CP9C Echelon modulating), 1 red flash (CP9C Echelon modulating). Watch the full pattern (short vs. long flashes) to tell them apart — all 4 are explained below.
Code 1 red flash: Flame was sensed when there was no call for heat
Flame was sensed when there was no call for heat. The control saw a burner flame while the gas valve should have been closed, so it runs the inducer and the blower to clear the heat exchanger.
Manual wording: “1 RED FLASH: This indicates that flame was sensed when there was not a call for heat. The control will turn on both the inducer motor and supply air blower. Check for a leaking or slow-closing gas valve.”
Documented for: TG8S, TGLS, TG9S, TM8X, TMLX, TM9X, TM8T, TM9T, TM8V, TM9V
Likely causes, most common first
- Leaking gas valve
- Slow-closing gas valve
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
This means gas may be reaching the burners when it should not. Call a licensed technician right away - the gas valve has to be tested and replaced by a professional.
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 TM9T*MP (96% AFUE Two Stage Multi-position), 505309-UIM-D-0511 (Johnson Controls Unitary Products (Coleman), TM9T*MP 96% AFUE two-stage PSC gas furnaces (TM8T*MP / TMLT*MP manual 521271-UIM-D-1211 carries the same table)) · checked 2026-08-25
Code 1 green flash (CP9C Echelon modulating): Normal operation with no call for heat
Normal operation with no call for heat. Standby.
Manual wording: “One Green Flash - Normal Operation with no call for heat.”
Documented for: CP9C Echelon modulating furnaces
Likely causes, most common first
- Normal standby
What you can safely check yourself
- If the house is cold, check the thermostat is set to HEAT and above room temperature
When to call a technician
No service needed.
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
Full page for Coleman code 1 green flash (CP9C Echelon modulating)
Code 1 amber flash (CP9C Echelon modulating): Normal operation with a call for cooling
Normal operation with a call for cooling. Not a fault.
Manual wording: “One Amber Flash - Normal operation with call for cooling.”
Documented for: CP9C Echelon modulating furnaces
Likely causes, most common first
- Normal air conditioning operation
When to call a technician
No service needed.
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
Full page for Coleman code 1 amber flash (CP9C Echelon modulating)
Code 1 red flash (CP9C Echelon modulating): Flame is present with no power being supplied to the gas valve - gas is reaching the burners when it should not be
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
Full page for Coleman code 1 red flash (CP9C Echelon modulating)