PCV stands for positive crankcase ventilation. When your engine ignites gasoline in the cylinders, some of the gases produced make their way into the crankcase, where oil is held to lubricate the engine. In earlier days, those gases would be vented out through a hose and go directly into the air. It was a waste of gasoline (since about three-fourths of the gases were unburned fuel) and a nasty source of pollution.

So engineers devised a one-way valve that directed those gases back into the engine's air intake system to be burned again. After a while, the PCV valve can get clogged up with gummy oil. Not only does that reduce the recirculation of the gases, but it can also cause pressure in the crankcase to increase and possibly lead to an oil leak.

Signs your PCV valve has failed are oil leaks around the engine compartment or under your vehicle and poor engine performance. Your fuel economy will get worse. If you notice those signs, we can check your PCV valve. 

At the same time a technician inspects the PCV valve, they'll also check the vacuum hose that runs back to the air intake. Plus, they'll make sure the vehicle doesn't have any other engine problems that might be contributing to your issues. 

Many technicians recommend replacing your PCV valve with each major tune-up, so you get ahead of any problems before they develop. Now that you're an expert on PCV, it may be time to check out those PVC pipes in your bathroom!