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 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 or other items that may cause a false reading.
• Check flame sensor Microamps with the burners off.
  • No Microamp signal but controller locks-out = Bad Control Board