York Furnace 7 Red Flashes (YP9C Modulating)
Soft lockoutShown as: Seven red flashes, two-second pause, repeating
Lockout due to no ignition. The control tried three times to light the burners and failed, so it locks out for one hour and then tries again.
Manual wording: “Seven Red Flashes - Lockout due to no ignition. The control will try three times for ignition. If flame cannot be established in three tries, the control will lockout for one hour and then will try again to light.”
Documented for: YP9C, YPLC modulating furnaces
Likely causes, most common first
- No or low gas supply
- Failed hot surface ignitor
- Faulty gas valve
- Dirty or faulty flame sensor
What you can safely check yourself
- Check that other gas appliances in the house still work
- Replace a dirty air filter
- Check the outside vent and intake pipes for blockage
- Cycle the furnace off and on once at the service switch to let it retry
When to call a technician
Ignitor, flame sensor and gas valve work all happen inside the live gas compartment. 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