York Gas Furnaces: TG9S Re: Diagnostic Codes / Fault Codes 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...

York Gas Furnace: TG9S/GY9S Re: Flashing Code 1 Code 1 = Flame sensed with no call for heat. In a Code 1 situation, the furnace control board thinks that the gas valve is stuck on and the flame is still burning without a call for heat. Therefore, when a control board goes into a code 1, it...

York Gas Furnace: TG9S/GY9S Re: Flashing Code 2 Code 2 = Pressure switch stuck closed The furnace pressure switch should only close when the inducer fan output is energized. If control board is not energizing the inducer fan output and the pressure switch circuit is closed, the board will...

York 90% Gas Furnace: TG9S Re: Flashing Code 3 Code 3 = Furnace Pressure Switch failed to close on a call for heat. ►The code description on the blower door says, "Vent or Termination Problem" which is a possible cause, but not the most likely. This gas furnace has two pressure switches: ...

York Gas Furnace: TG9S/GY9S Re: Flashing Code 4 Code 4 = Limit switch open If the limit control opens, the burners will be de-energized and the air circulation and vent blower will be turned on until the limit closes. The diagnostic light code for this is four short flashes followed by a...

York Gas Furnace: TG9S/GY9S Re: Flashing Code 6 Code 6 = Pressure switch opened (Code 3) 4 times during a run cycle. ► This is a "Soft Lockout" which will automatically reset after 1 hour. Qty Possible Causes: 3 Water in Inducer 1 Improper Condensate Drainage 1 ...

York Gas Furnace: TG9S/GY9S Re: No Heat - Flashing Code 7 Code 7 = Three consecutive failed ignition attempts (failed to sense flame). ► This is a "Soft-Lockout" which will automatically reset/retry after 1 hour. Qty Possible Causes: 10 Dirty Flame Sensor 3 Bad...

York Gas Furnace: TG9S/GY9S Re: No Heat - Flashing Code 8 Code 8 = Flame was established but later lost - 5 times. ► This is a Soft-Lockout which will automatically reset after 1 hour. Qty Possible Causes: 2 Dirty Flame Sensor Clogged Burners No or Low Gas...

York Gas Furnace: TG9S/GY9S Re: Flashing Code 10 / Fault Code 10 Code 10 = Flame sensed with no call for heat. ► The furnace control board thinks that the gas valve is stuck on and flame is still burning without a call for heat. Therefore, when a control board goes into a Code 10, it will...

York Gas Furnace: TG9S/GY9S Re: Flashing Code 11 This indicates that a primary or auxiliary limit switch has opened and has remained open for more than five minutes. This condition is usually associated with an air circulation failure. ► Code 11 is a Hard-Lockout which requires cycling...