PCV Valve

Symptoms of a Bad PCV Valve

The positive crankcase ventilation (PCV) valve is an engine component typically located on the engine valve cover or intake manifold. PCV valves are designed to direct oil vapor and excess pressure from the crankcase back into the intake manifold where it's burned off through the combustion process. PCV valves are designed to remain closed to minimize oil loss through evaporation, and open with the rising force of oil vapor to reduce internal engine pressures. The recirculating of oil vapor through the PCV valve helps reduce harmful emissions and increases combustion efficiency. By regulating the flow of excess oil vapor through the crankcase, the PCV valve also helps prevent the buildup of oil pressure in the engine, which can cause excessive force on seals and gaskets which could otherwise cause a damaged seal or gasket and an oil leak. Over time, a clogged or malfunctioning PCV valve can cause increased oil consumption, poor fuel economy, rough idling, oil leaks, or an active Check Engine light. It is often easy to test a PCV valve to determine if it is functioning properly by removing and shaking the valve. If you can hear the check ball moving inside the valve, it means that it is free and able to open and close as needed. You can learn more about how to diagnose and replace a PCV valve with our helpful video. If you are repairing an oil leak or need a replacement PCV valve, O'Reilly Auto Parts offers a selection of PCV valves, gaskets, seals, and PCV hoses for most vehicles.