Diagnostic Aids

WARNING: This page is about a different car, the 2002 GMC Sierra and 2002 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

Use a scan tool in order to clear information. Run the EGR flow test in order to verify a repair. Keep the following items in mind when running the EGR flow test:

The PCM runs the EGR flow test during a gradual deceleration.
The PCM runs the EGR flow test during a closed throttle condition.
The PCM runs the EGR flow test at vehicle speeds between 26-70 MPH.
Several deceleration cycles may be necessary to run a sufficient number of EGR flow test samples (9-13).

Inspect for the following conditions:

Vacuum restriction to the MAP sensor. A restriction to the MAP sensor can cause the EGR flow test to fail due to insufficient MAP changes being monitored during the test. Inspect for objects blocking the vacuum to the MAP sensor.
An engine that is running poorly may cause this DTC to set.
Poor connection or damaged harness. Inspect the wiring harness for damage.
If the harness appears to be okay, observe the Actual EGR Position display on the scan tool while moving connectors and wiring harnesses related to the EGR valve. A change in the display indicates the location of the malfunction.

Reviewing the Failure Records vehicle mileage since the diagnostic test last failed helps determine when the condition that caused the DTC to be set occurred. This may assist in diagnosing the condition.