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 will lock the inducer motor and blower motor on.

CHECKOUT:

1. Check Gas Valve

• Start the furnace with a call for heat
• After the burners have been lit for at least 30 seconds, remove the "W" wire.
  • The burners should extinguish immediately.
    • Delayed shut-off = Sticking Gas Valve

2. Check Flame Sensor

• Visually check the flame sensor for rust flakes or other items that may cause a false reading.
• Check flame sensor Microamps when the burners shut-off.
  • No Microamp signal but controller locks-out = Bad Control Board