Crankcase Emission Control System: Inspection

After disconnecting the vapor hose from the PCV valve, remove the PCV valve.
Reconnect the PCV valve to the vapor hose.
Run the engine at idle, and put a finger on the open end of the PCV valve and make sure that intake manifold vacuum can be felt.
NOTE: The plunger inside the PCV valve will move back and forth at vacuum.

Fig 1: Putting Finger On Open End Of PCV Valve
Courtesy of HYUNDAI MOTOR CO.
If the vacuum is not felt, clean or replace the vapor hose.