As your Subaru engine starts running its crankcase, it begins to collect combustion chamber gases which leak past the rings surrounding pistons and sealing them to the cylinder walls. These gases contain compounds that are harmful to your engine, particularly hydrocarbons; which are the unburned fuel, as well as carbon dioxide. It also contains a significant amount of water vapor that if it remains too long in your vehicle crankcase, it will begin to condense out of the air within your crankcase and eventually will form corrosive acids and sludge on the engine's interior surfaces. This can certainly damage your vehicle engine causing it to clog small inner passages, overheating, poor lubrication, and high emissions levels. This is what your Subaru PCV valve is all about. In order to prevent all these troubles that might happen to your vehicle, equipping your vehicle with a PCV valve that serves as the ventilation system in your vehicle crankcase necessitated. Your Subaru PCV valve is only one part of your emission system that is basically a variable and calibrated air leak, wherein your vehicle engine returns its crankcase combustion gases. Instead of the gases being thrown up into the atmosphere, gases are being rerouted back into your vehicle intake manifold, to re-enter the combustion chamber as part of a fresh charge of air and fuel. Because of the importance of its function to the cycle of your air and fuel mixture, when it gets bad, it can definitely affect the performance of your vehicle, particularly its combustion process. So whenever your Subaru PCV valve shows an indication of wearing, better check it at once. If it is positive from any sort of damage, replace it with a new and high quality replacement PCV valve. Searching for that kind of replacement is easy through on our online catalog.