York Furnace 8 Red Flashes (YP9C Modulating)
Soft lockoutShown as: Eight red flashes, two-second pause, repeating
Lockout due to too many flame recycles - the flame was lost five times during a single heating cycle. The control locks out for one hour, then tries again.
Manual wording: “Eight Red Flashes - Lockout due to too many flame recycles. This flash code occurs if flame is lost five times during a single heating cycle.”
Documented for: YP9C, YPLC modulating furnaces
Likely causes, most common first
- Faulty gas valve
- Low gas pressure
- Dirty flame sensor
What you can safely check yourself
- Check that other gas appliances in the house still work
- Replace a dirty air filter
When to call a technician
Gas pressure and flame sensor checks require a manometer and live-burner access. Call a technician.
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