Positive Crankcase Ventilation (PCV) System
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2003 Lexus SC 430, 2003 Lexus RX 300, 2003 Lexus LX 470, 2003 Lexus LS 430, and 2003 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
On some vehicles, PCV valve is referred to as Ventilation Valve.
Positive Crankcase Ventilation (PCV) system prevents crankcase vapors from escaping into atmosphere. Crankcase vapors are routed from crankcase through a vacuum-controlled PCV valve and then delivered back into cylinders. PCV system provides primary control of crankcase blow-by vapors, according to manifold vacuum. When manifold vacuum is high (at idle), PCV restricts vapor flow to maintain a smooth idle condition.