In order to keep the PCV system working well, clean hose and check the PCV valve as scheduled in maintenance. The PCV valve is threaded into the rear side of the intake plenum which sits on top of the back side of the intake plenum under cowl. Start engine and let it idle then remove hose from PCV valve. You should be able to hear a hissing sound from it. Cover your finger over it and feel for suction. If you can get vacuum, then your PCV valve if doing its work well. In case there is no vacuum, replace the PCV valve. Clean or change a cracked or obstructed PCV hose.