Diagnostic Aids

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

For any test that requires probing the PCM or probing a component harness connector, use the Connector Test Adapter Kit. Using this kit prevents damage to the harness or component terminals.
Carbon build-up in the exhaust manifold may restrict the amount of air flow necessary to affect the HO2S voltage. If you suspect this condition, remove the air pipe from the manifold and inspect the passage.
For an intermittent condition, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.
Inspect for the following conditions:
1. Excessive exhaust system back pressure.
2. Moisture, water, or debris ingestion into the AIR pump.
3. Leaking check valves will leave traces of exhaust carbon in the AIR system.
4. A vacuum solenoid leaking vacuum will hold the shut-off valve open an exhaust noise may be heard through the air cleaner fuel trims at idle may be higher than normal a DTC may not set.
5. The vacuum lines at the vacuum solenoid cannot be reversed.
6. A check valve that flows in both directions causes heat damage to the AIR system components.