What is the primary function of a positive crankcase ventilation (PCV) system?

The primary function of a positive crankcase ventilation (PCV) system is to reduce vehicle emissions. This system works by redirecting gases that escape from the combustion chamber and accumulate in the crankcase back into the intake manifold, where they can be burned in the engine. By doing this, the PCV system ensures that harmful pollutants do not escape into the atmosphere, thereby lowering the overall emissions from the vehicle.

A well-functioning PCV system is essential for vehicle compliance with environmental regulations as it helps to control hydrocarbon emissions, which are significant contributors to air pollution. While other outcomes such as improved combustion efficiency and enhanced performance may occur as secondary effects of a well-maintained PCV system, the core purpose of the system is indeed focused on emissions reduction. This is why the selection correctly points to the reduction of vehicle emissions as the primary function.