Circuit Description

WARNING: This page is about a different car, the 2003 GMC Sonoma and 2003 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.

The Secondary Air Injection (AIR) system is designed to reduce exhaust emissions during engine starts. The PCM activates the AIR system by supplying a ground to the AIR pump relay. This action energizes the AIR pump and the vacuum control solenoid, applying vacuum to the AIR shut-off valve, opening the valve. The AIR pump then forces air past the shut-off valve, through the pipes/hoses and the exhaust check valve into the exhaust system to accelerate catalyst operation. When inactive, the shut-off valve prevents airflow in both directions. The PCM will perform a passive test while the AIR system is performing normally. During the test the PCM monitors the O2S voltages, expecting a drop below 100 mV, approaching about zero mV. The PCM expects the short term Fuel Trim (FT) to increase at the same time. If the test fails or is inconclusive, the PCM will run up to 3 diagnostic active tests using the O2S voltage parameter and short term FT parameter to verify the system operation. When PCM detects an insufficient O2S response, DTC P0410 sets.