Diagnostic Aids

WARNING: This page is about a different car, the 2001 GMC Savana, 2001 Chevrolet RV Cutaway, 2001 Chevrolet Cutaway, and 2001 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.

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

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

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