Thats called a wax element. It opens the hot air door to the exhaust manifold when the engine is cold thus your engine warms quicker and produces less emissions. The quicker your engine warms up the sooner the computer can take over and get a signal from the sensors making it run as efficient as it can. The problem with the wax element is that it fails eventually and your hot air door in your air box only lets hot air in all the time. The result is that your AMM or Air Mass Meter fails. You can remove your airbox and the wax element. Then remove the shiny metal rod from the wax element. Take a nail that is longer than the rod you removed and shove it in the wax element. It has to be just longer so that is keeps the door shut in your air box to hot air from the manifold. Then replace the wax element with the nail in place. That way your engine will only breath cold air all the time and smog technicians will not even know. There is one problem. If you live in a cold climate, your throttle plate may ice. By the way, thats why AMM fail on 240 Models. Good Luck!