These York modulating 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:
1 Green	Normal Operation - no call for heat
2 Green	Indicator for "No error codes in memory".	See Diagnostic Fault Code Storage and Retrieval section below.
3 Green	Indicator for "Error codes cleared from memory".	See Diagnostic Fault Code Storage and Retrieval section below.
Rapid Green	Control is in "Factory Speed-up" mode.	This mode is used only during factory run-testing of the furnace. To stop this mode, cycle power to the furnace off and then back on.
1 Amber	Normal Operation - with a call for COOLING
2 Amber	Normal Operation - with a call for HEATING
3 Amber	Normal operation, burner is on at end of heating cycle after wall thermostat has been satisfied.
4 Amber	Heating capacity is reduced due to restriction in the circulating air system.	Check for dirty filter or closed registers.
5 Amber	Heating capacity is reduced due to restriction in the combustion air or vent system.	Check for blocked vent/air pipe or clogged condensate drain.
6 Amber	Normal operation with call for HEAT PUMP heating.
Rapid Amber	Low flame sense current.	Check for dirty or mislocated flame sensor rod.
Steady Red	Control fault has been detected or there is 24 volts present without 115 volts.	Check that there is 24 volts and 115 volts being supplied to the board. If so, then the board should be replaced.
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	Bad limit Low airflow Over-Fired
5 Red	Rollout switch open / open fuse	Bad switch Cracked heat exchanger Bad inducer motor Over-Fired
6 Red	Gas valve communication error	Bad wiring to valve Bad air pressure sensor Check pressure switch hose connection
7 Red	Ignition lockout due to 3 retries	Bad igniter Dirty flame sensor No gas flow
8 Red	Flame signal lost 5 times	Dirty flame sensor Combustion air problem
9 Red	Grounding or line polarity fault	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	ID plug is not present or not connected properly

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: 598

Last updated: 8 Feb, 2019

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