What does replacing the PCV valve mean?

[LenaRose]

PCV stands for Positive Crankcase Ventilation, which refers to the positive ventilation control system for the crankcase (or oil pan). The PCV valve consists of a valve body, valve, valve cover, and spring, and is non-disassemblable. Its main functions are: to direct gases from the crankcase into the intake manifold via the PCV valve, with a small amount of air entering the intake manifold directly from the air filter through the PCV valve. This prevents icing at the throttle, incomplete combustion, and worsening emissions. It also prevents exhaust gases from entering the atmosphere and keeps the engine oil from deteriorating. At the end of the engine's power stroke, some unburned mixture leaks into the crankcase under high pressure through the piston rings, a phenomenon known in the industry as 'blow-by.'