Which type of vehicles must have a closed PCV system?

Vehicles manufactured in 1990 and newer are required to have a closed Positive Crankcase Ventilation (PCV) system. This requirement aligns with advancements in automotive emissions control technologies aimed at reducing pollutants released into the atmosphere. The closed PCV system allows for the recycling of gases from the crankcase back into the engine for combustion, thereby minimizing the release of harmful emissions.

In vehicles manufactured before 1990, designs were less stringent regarding emissions control, and many relied on open systems that vented crankcase gases directly into the atmosphere. Consequently, the modern closed PCV systems are a standard in newer vehicles to help meet various environmental regulations, including those set forth by the EPA.

Other vehicle categories presented in the options are not universally required to have a closed PCV system, as not all hybrids or diesel engines, for instance, will have the same specifications and requirements as those applied to vehicles made from 1990 onwards.