Air Injection: Description and Operation

Fig. 51 Secondary air supply system diagram:

Secondary air is used by the catalytic converter to complete oxidation and reduction of exhaust gas emissions. The secondary air supply system uses an electric secondary air control solenoid valve controlled by the ECU which in turn controls vacuum to a secondary air control valve, Fig. 51. When the engine coolant is cold (15 to 63°C or 59 to 145°F) or when the vehicle is decelerating, the secondary air control valve is open allowing secondary air to pass through the reed valve and into the exhaust system.