EMISSION CONTROL SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


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

      Component Function
      Exhaust Emission Control System ECM Determines an optimal fuel injection volume based on the signals from various sensors.
      Three-Way Catalyst (TWC) Reduces CO, HC and NOx in the exhaust gas.
      Oxygen Sensor Detects the oxygen concentration in the exhaust emissions by measuring the electromotive force generated in the sensor itself. For details, see the 2TR-FE ENGINE CONTROL section.
      Air Fuel Ratio Sensor
      Air Injection System* Air Pump Assembly Uses a built-in DC motor to supply air to the air switching valve.
      Air Switching Valve Assembly Introduces air that is pumped by the air pump into the exhaust manifold.
      Air Pressure Sensor Detects the air injection pressure.
      Air Injection Control Driver

      • Activated by the ECM, the air injection control driver actuates the air pump and the air switching valve.

      • Detects an input-output circuit failure at the air injection control driver and transmits it to the ECM.
      ECM

      • Controls the air injection system in accordance with signals from the crank position sensor, engine coolant temperature sensor and intake mass air flow meter sub-assembly.

      • Receives a failure detection signal from the air injection control driver and stores a corresponding DTC in memory.
      Evaporative Emission Control System ECM Sends signals to the VSV (for EVAP) to control the purge flow.
      Charcoal Canister Sub-assembly Contains activated charcoal to absorb the fuel vapor created in the fuel tank.
      Duty Vacuum Switching Valve (for EVAP) Opens in accordance with the signals from the ECM when the system is purging, in order to send the fuel vapor that was absorbed by the charcoal canister into the intake manifold.

      • *: Models with air injection system