Positive Crankcase Ventilation (PCV) System

When the engine is operating (usually under load), the positive crankcase ventilation (PCV) system captures any oil vapor or raw hydrocarbons that may escape past the piston rings into the crankcase during combustion. The PCV system is a set of tubes, containers, and one-way PCV valves designed to capture, hold, and recycle these vapors back into the combustion process, where they are burned as fuel.