York Furnace: 10 Flashes
A York furnace LED pattern starting with 10 flashes matches 2 documented codes: 10 red flashes, 10 red flashes (YP9C modulating). Watch the full pattern (short vs. long flashes) to tell them apart — all 2 are explained below.
Code 10 red flashes: The gas valve is energized with no call for heat
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, TG9S, TM9E, TM9X, TM8X, TM9T, TM8T, TM9V, TM8Y, TM9Y
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 York furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- Installation Manual - Single Stage PSC Residential Gas Furnaces, TG9S and GG9S Series (95.5% AFUE Multi-position), 1083287-UIM-A-0114 (Johnson Controls Unitary Products (York), TG9S*MP, GG9S*MP single-stage PSC 95.5% AFUE gas furnaces) · checked 2026-08-25
- Installation Manual - Single Stage PSC Residential Gas Furnaces, TG8S*MP / TGLS*MP / GG8S*MP / GGLS*MP (80% AFUE Multi-position / Standard Low NOx), 998491-UIM-B-1013 (Johnson Controls Unitary Products (York), TG8S*MP, TGLS*MP, GG8S*MP, GGLS*MP 80% AFUE single-stage gas furnaces) · checked 2026-08-25
- Installation Manual - Single Stage ECM Residential Gas Furnaces, TM9E Series (95% AFUE Multi-position), 1083163-UIM-A-0214 (Johnson Controls Unitary Products (York), TM9E*MP single-stage ECM 95% AFUE gas furnaces) · checked 2026-08-25
- Installation Manual - Two Stage Variable Speed ECM Residential Gas Furnaces, TM9V Series (96% AFUE Multi-position), 1083294-UIM-A-0114 (Johnson Controls Unitary Products (York), TM9V*MP two-stage variable-speed ECM 96% AFUE gas furnaces) · checked 2026-08-25
Code 10 red flashes (YP9C modulating): Gas valve circuit shorted
Gas valve circuit shorted.
Manual wording: “Ten Red Flashes - Gas valve circuit shorted. Check gas valve wiring. If correct, replace gas valve.”
Documented for: YP9C, YPLC modulating furnaces
Likely causes, most common first
- Shorted gas valve wiring
- Failed 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
A shorted gas valve circuit is a gas-safety fault. Call a licensed technician and do not keep cycling the furnace.
A York furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Installation Manual - Modulating ECM Residential Gas Furnace with ECM Motor, Models YP9C*C / TP9C*C / CP9C*C / LP9C*C (Up to 98% Modulating Multi-position), 1083292-UIM-A-0114 (Johnson Controls Unitary Products (York), YP9C*C (York Affinity modulating), and the identical TP9C / CP9C / LP9C chassis) · checked 2026-08-25