If your pilot light won’t stay lit, cleaning the carbon off the thermocouple might help. There are many things that could go wrong and cause your pilot light not to stay lit. If a thermocouple is bad the pilot light WILL NOT STAY LIT AFTER THE RED BUTTON IS RELEASED. Forced air furnace who's pilot won't stay lit, not the thermocouple [ 1 Answers ] Pilot won't stay lit beyond releasing the button to light it. The thermocouple was used to hold the pilot valve open. The pilot can go out for a number of other reasons, however, so if you're having trouble getting the pilot to stay lit , the thermocouple may not be at fault. It’s designed to determine whether the pilot light is lit and then subsequently signals the gas valve to open. Its not putting enough voltage through to the valve to tell it its lit. 1. Pilot does not light or stay lit after knob is released - Check carefully that gas to appliance is on and that the valve is in the correct (pilot) position and fully depressed when lighting. After years of use, your thermocouple may have a buildup of carbon deposit, which affects its ability to function. Tested for power at the transformer--OK. According to the check list posted on the unit, it says that if the thermocouple has been changed and the pilot light will not remian lit, the next item is the valve body. It consists of a heat sensor connected to a solenoid; when the sensor is not heated by the pilot flame, the solenoid closes the gas supply line. Nothing lasts forever, and when the thermocouple wears out, the pilot won't stay lit and your appliance won't work. Issue #1: Bad thermocouple A furnace thermocouple is a safety feature that regulates gas flow to your system based on whether or not the pilot light is on. If pilot ignites but does not stay lit after knob is released, then the problem is with the thermocouple not generating enough voltage to the valve. Usually if the thermocouple is toast the pilot doesn't even stay lit. If the pilot valve is closed the main valve would not open. If my Thermocouple is bad will my pilot light stay lite. They are dependent on one another, totally. When a thermocouple fails, the pilot light won't stay … Odd though. The job of the thermocouple is to keep the pilot lit. Everything looks good and I too think it could be the gas valve that is gone bad. The thermocouple can do this because, in its probe, it contains two different metals, and a … If the pilot is staying lit but the burners won't light the thermocouple is likely toast. A standing pilot gas valve has two inner valves, one for the pilot light and one for the main valve. It does this by sending a tiny electric current to a sensor on the gas valve signaling the valve to stay open. 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