York Furnace 10 Red Flashes (YP9C Modulating)
Safety faultShown as: Ten red flashes, two-second pause, repeating
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