Circuit Description

AIR system is used to accelerate the heating process of the catalytic converters by introducing outside air into the exhaust system. Air pump operates on cold engine starts. PCM independently controls the ground for the air pump relay coil and air pump solenoid. During air pump operation, O2S1 should read lean, indicating that air pump is working. DTC will set when PCM command AIR system on and O2S1 signal does not indicate a lean condition for certain length of time.