Positive Crankcase Ventilation: Testing and Inspection

The crankcase ventilation hose is connected to the intake manifold in order to extract oil vapor from the crankcase. If the oil level is too high or the oil is contaminated with petrol, the fuel/air mixture will become too rich. This will affect long term fuel trim.

Diagnostic trouble codes (DTCs) can be posted if the car is driven with contaminated engine oil.