VIN Range: M45255->N52206

Engine Emission Control - VIN Range: M45255->N52206

Positive Crankcase Ventilation System

Vehicles fitted with 4.2L engine
On vehicles fitted with a 4.2L engine the positive crankcase ventilation (PCV) system consists of a PCV valve, and two PCV hoses. The PCV valve is mounted on the right-hand valve cover and a hose is connected between PCV valve and the throttle body elbow. The PCV valve regulates the amount of ventilation air and crankcase gas supplied to the intake manifold and also prevents backfiring into the crankcase. The left-hand valve cover PCV hose is connected to the air cleaner outlet pipe.

Vehicles fitted with 2.5L and 3.0L engine
On vehicles fitted with 2.5L and 3.0L engine the PCV system consists of two hoses, connected between the right-hand valve cover and the intake manifold and the left-hand valve cover and the air cleaner outlet pipe.

The PCV system recycles crankcase gases back through the engine where they mix with incoming air/fuel charge.

The positive crankcase ventilation system helps to reduce hydrocarbon emissions from the engine.

Exhaust Gas Recirculation System

Exhaust Gas Recirculation (EGR) Valve







Exhaust Manifold to Exhaust Gas Recirculation (EGR) Valve Tube







The exhaust gas recirculation (EGR) system is fitted on all vehicles fitted with a 4.2L engine. It comprises of an EGR valve and exhaust manifold to EGR valve tube. The EGR system allows a measured quantity of exhaust gas to be directed back to the intake manifold. The exhaust gas is introduced to the incoming charge in the intake manifold, where it mixes with the air/fuel mixture and lowers the peak gas temperature, reducing nitrogen oxide (NOX) exhaust emissions. The gas is drawn through the exhaust manifold to EGR valve tube from the exhaust to the inlet manifold via the EGR valve. The EGR valve is electrically operated and is controlled via an input from the engine control module (ECM).

On vehicles without super charger the EGR valve is mounted on the intake manifold. On vehicles with supercharger the EGR valve is mounted on the throttle body elbow.

The ECM can monitor the operation of the EGR system by receiving inputs from the manifold absolute pressure (MAP) sensor. The MAP sensor monitors the EGR flow by the change in intake manifold pressure when the EGR valve is operated. If at any time the input signal to the ECM exceeds pre-defined thresholds due to low pressure reading for a calibrated period of time, a diagnostic trouble code (DTC) is recorded.

On vehicles without super charger the MAP sensor is mounted on the rear of intake manifold. On vehicles with supercharger the MAP sensor is mounted on the rear of the throttle body elbow.