Crankcase Emission Control (PCV) System: Inspection

Remove the PCV valve.
Insert a thin stick (A) into the PCV valve (B) from the threaded side to check that the plunger moves.
If the plunger does not move, the PCV valve is clogged. Clean it or replace.

Fig 1: Testing PCV Valve Operation
Courtesy of KIA MOTORS AMERICA, INC.