Circuit Description

WARNING: This page is about a different car, the 2004 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.

The Secondary Air Injection (AIR) System is designed to lower exhaust emission levels on initial start up. The AIR pump runs until closed loop is achieved.

The powertrain control module (PCM) commands the AIR pump relay and the AIR vacuum solenoid ON simultaneously by supplying a ground on the AIR pump relay control circuit and a ground to the AIR vacuum solenoid control circuit. When engine vacuum is applied to the AIR shut-off valve, airflow from the AIR pump flows through the pipes/hoses to the exhaust check valves. The air enters the exhaust stream, accelerating catalyst operation. When inactive, the exhaust check valves and the AIR shut-off valve prevent airflow in either direction.

The PCM detects a system airflow problem by monitoring the heated oxygen sensors (HO2S) during normal AIR system operation. This is a passive test. If the passive test indicates a pass, the PCM takes no further action. If the passive test fails or is inconclusive, the diagnostic will proceed with an intrusive or active test. The PCM will command the AIR system ON during closed loop operation under normal operating conditions. The active test will pass or fail based on the response from the HO2S. A lean HO2S response indicates that the secondary AIR system is functioning normally. An increasing short term fuel trim (FT) value also indicates a normally functioning system. The AIR diagnostic consists of the passive test and the active tests. The AIR diagnostic requires failure of the passive and active tests on two consecutive key cycles to illuminate the MIL and store a DTC. If the PCM detects that the HO2S and Short Term FT did not respond as expected on both of the engine banks, DTC P0410 sets.