The pilot light on my natural gas furnace keeps going out what could the problem be?

It could be the thermocouple is weak but it is more likely a dirty pilot not keeping the the thermocouple properly heated. If the flame on the pilot has a lazy yellow tip and is not a strong blue flame burning over the top 1/8 of the thermocouple it needs to be cleaned.

Make sure the combustion process (including the pilot) has a good supply of combustion air. Check your furnace filters. Sometimes the filters are plugged and the filter track compartment has no door to seal it properly. If the filter is partially plugged, the blower could be sucking air from the unsealed filter doorway...thus making the pilot unstable and causing it to go out. The most likely problem with the pilot though, if the furnace is just an old standard furnace with a standing pilot, is that it needs a new thermocouple...at the worst a new gas valve. Also, when the pilot is lit, check for proper pilot flame characteristics.... The flame should be mostly blue ...with some orange possible. You dont want any yellow or white in the flame. If you see yellow or white, take a big screwdriver and tap the pilot assembly right beside the flame. Alot of times this cleans the pilot. Also be careful you dont have a cracked heat exchanger making your pilot go out. With the blower compartment and filter door sealed... check for pilot flame stability with the fan on, then with the fan off. If the the pilot flame starts dancing around irratically when you put the blower on, then goes still again when you switch of the blower fan...you could have a cracked heat exchanger.

Try this first: Get a butane torch and heat up the tip of that pilot real good. Chances are it will stay working if not, go down to ace hardware and get the guy to sell you a thermocouple it is less than 10 bucks. What it is is a copper safety device that produces a small amount of current to hold open the gas so the pilot will stay lit and the heater will come on. When you move the knob to PILOT and mash down on it you are pushing down on a spring loaded valve with an electro magnet in it. The flame causes energy to hold the magnet in. If the pilot blows out the magnet will not hold and the spring will shut the flow of gas off so the house wont blow up. It is that simple.It has a 3/8th nut on the end that screws into the gas valve, It is not gas carrying so no gas will come out. The old thermocouple will slide out of the pilot assembly and the new one will slide in. Make sure the flame hits the tip and not the middle. The nickle/copper element in the tip produces electrical current which holds the gas open as long as the pilot is lit. Clever huh? TY Ralph Nader.

If your furnace is vented by a electric fan...there are pressure sensors that will prevent lighting if the flue is blocked (nest for example). I had a similar problem...except my unit is in the attick. Moisture had collected (almost none at all actually)...I removed the rubber tubing (about 1/4" thick) and tapped it out and the water flung out. the tubes went to the pressure switches..silver disk shaped.

If you have a pilot light...the thermo-couple could be replaced cheaply...just make sure you get the tip back into the same location inside the pilot light flame.

agreed sounds like a thermocouple

sounds like a bad thermocouple to me

I concur doctor it is the thermocoupler

get a new furnace

change the thernocouple and filter

i think freddie is right