Excessive CO or HC During Idle

1. Faulty ignition system.
2. Defective air flow sensor.
3. Open or shorted intake air temperature sensor.
4. Defective coolant temperature sensor.
5. Closed secondary air control solenoid.
6. Defective pressure sensor.
7. Open idle position switch.
8. Shorted throttle position sensor.
9. Defective oxygen sensor.
10. Defective ECU.
11. Defective pressure exchange solenoid valve, if equipped.