York Furnace Rapid Amber Flash (YP9C Modulating)
WarningShown as: Amber LED flashing rapidly
Low flame sense current. The control can barely detect the burner flame.
Manual wording: “Rapid Amber Flash - Low flame sense current. Check for dirty or mislocated flame sensor rod.”
Documented for: YP9C, YPLC modulating furnaces
Likely causes, most common first
- Dirty flame sensor rod
- Mislocated flame sensor rod
What you can safely check yourself
- Replace a dirty air filter
- Check the outside vent and intake pipes for blockage
When to call a technician
Cleaning or repositioning the flame sensor is done inside the live burner compartment. Call a technician before this turns into a no-heat lockout.
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