1. Check the ventilation system valve, hoses and connections for leaks and blockages.
2. At idle, squeeze the hose between the crankcase ventilation valve and the intake manifold with your hands or pliers, make sure that the valve makes a click.
If the valve does not click, check the valve washer for damage. If the washer is OK, replace the crankcase ventilation valve and check again.
3. Replace the crankcase ventilation valve.
Disconnect the hose and unscrew the valve. Install the valve with a new gasket.