EMISSION CONTROL SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


    1. The main components of the exhaust emission control system are as follows:

      Component Function
      TWC

      Oxidizes CO and HC in the exhaust gas and deoxidizes NOx at the same time, to purify them into CO2, H2O and N2.
      Air Fuel Ratio Sensor Determines the concentration of oxygen remaining in the exhaust gas. Has a characteristic where its output is proportional to the engine air fuel ratio. Located upstream of the catalytic converter.
      No. 2 Air Fuel Ratio Sensor Detects the oxygen concentration in the exhaust gas by measuring the electromotive force which is generated in the sensor itself. Located downstream of the catalytic converter.
      ECM Controls the volume of fuel consumed based primarily on the signal from the air fuel ratio sensor, with minor corrections based on the signal from the No. 2 air fuel ratio sensor. This control optimizes the exhaust emissions.