PCV Valve
WARNING: This page is about a different car, the 2002 Hyundai XG350, 2002 Hyundai Sonata, 2002 Hyundai Santa Fe, 2002 Hyundai Elantra, and 2002 Hyundai Accent. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect vacuum hose from PCV valve. Remove PCV valve from valve cover and reconnect to vacuum hose. Start engine and allow to idle. Cover open end of PCV valve with finger, and check for manifold vacuum. If manifold vacuum is felt, PCV valve is opening properly. If manifold vacuum is not felt, clean PCV valve, vacuum hose and/or replace as necessary.