How to clean thermocouple on gas fireplace. The thermocouple on a gas fireplace may eventually become clogged with dirt and soot which can reduce the effectiveness of the thermocouple and may eventually prevent the fireplace from lighting as expected. If cleaning the thermocouple didnt allow your pilot light to stay lit or cleaning the thermopile didnt allow the pilot light to generate enough electricity to open your gas valve and ignite the burner it might be time to replace one of them. Shut off the furnace gas to remove and clean the thermocouple if it is covered with soot.
Step 2 hold pilot open to heat thermocouple push in the control valve and light the pilot flame. The thermocouple on your gas furnace is a heat sensitive device that transmits a small electrical signal to the gas valve to keep it open when the pilot is on. Turn the gas back on and relight the pilot light.
Place the new thermocouple in the same place your old one sat and close up the fireplace to conduct a test. Locate the gas valve its usually behind a grill on the front of the fireplace and find the copper thermocouple wire leading from it.