Passat L4-1984cc 2.0L DOHC (1991)
EGR Temperature Sensor: Description and Operation
PURPOSE
Fig. 39 Egr Valve Location, 16V (California)
The EGR system is designed to reduce NOx emissions.
The three major components used in the EGR system are the:
EGR valve
Vacuum amplifier
Vacuum thermo-switch
The EGR valve is located on the back of the intake manifold. The function of the EGR valve is to control the amount of exhaust gas returned to the
combustion chamber to reduce the peak combustion temperature.
By reducing the peak combustion temperature, the formation of oxides of nitrogen (NOx) is reduced.
EGR VALVE OPERATION
Fig. 37 Vacuum Amplifier, 16V (California)
The EGR valve is opened by intake manifold vacuum via the vacuum amplifier. The purpose of the vacuum amplifier is to supply vacuum to the EGR
valve during acceleration (low manifold vacuum).
