Diagnostic Aids

WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

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.

In order to verify a repair, clear info with the scan tool and run the EGR flow test keeping the following conditions in mind:

PCM will only run the EGR flow test during a gradual deceleration.
PCM will only run the EGR test during a closed throttle condition.
PCM will only run the EGR test at vehicle speeds above 30 MPH.
Several deceleration cycles, typically 9-12, will be necessary to run a sufficient number of EGR flow test samples.
The EGR Test Counter displayed on the scan tool can be useful in determining that the EGR flow test is running and in order to keep track of the number of test samples taken. The counter will increment each time a test sample is taken.