These York gas furnaces have a control board inside the furnace blower compartment that will flash a diagnostic code that shows the operating status of the furnace.

Diagnostic Codes:
Slow Green	Normal Operation - no call for heat
Slow Amber	Normal Operation - with a call for HEATING
4 Amber	No power on "G" during a cooling cycle (power on "Y")	Check thermostat and low voltage wiring
Flashing Amber	Low flame signal	Flame signal below 0.35 microamps Check flame sensor Check gas pressure
Any Color - Steady On	Possible Faulty Control or Blown Fuse	Reset power - if steady light returns, replace control Steady Red indicates a blown fuse - Check low voltage fuse
1 Red	Flame present with gas off	Stuck gas valve Shorted flame sensor Faulty control
2 Red	Pressure switch stuck closed	Bad pressure switch Inducer fan relay stuck on
3 Red	Pressure switch stuck open	Bad pressure switch Bad inducer fan Bad inducer fan relay Blocked or restricted vent Condensate drainage issue
4 Red	Limit switch open / open fuse Limit opened 5 times during a heating cycle (1-Hour Lockout)	Bad limit Low airflow Over-Fired
5 Red	Rollout switch open / open fuse (Hard Lockout)	Bad switch Cracked heat exchanger Bad inducer motor Over-Fired
6 Red	Pressure switch opened 4 times in one heating cycle (1-Hour Lockout)	Bad pressure switch Bad inducer fan Bad inducer fan relay Blocked or restricted vent Condensate drainage issue
7 Red	3 failed ignition attempts (1-Hour Lockout)	Bad igniter Dirty flame sensor No gas flow
8 Red	Flame was established but later lost - 5 times in one heating cycle (1-Hour Lockout)	Dirty flame sensor Combustion air problem
9 Red	Grounding or line polarity fault	Look for loose or missing Ground wire Try reversing transformer power
10 Red	Gas valve circuit shorted	Check gas valve wiring
11 Red	Extended limit switch open	Bad limit Blower failure
12 Red	Igniter failure	Bad Igniter Bad board

Fault Code Retrieval: With no thermostat call push and release the LAST ERROR button. The LED will flash up to 5 stored fault codes, beginning with the most recent. If there are no codes in memory, the LED will flash two green flashes.

Clear the Fault Codes: Push and hold the LAST ERROR button for at least five seconds. The LED will flash three green flashes when the memory has been cleared.

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Article ID: 703

Last updated: 20 Apr, 2022

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