Diagnostic Aids

Inspect for the following conditions:

• An EGR valve that shows signs of excessive heat. Check the exhaust system for blockage or for a plugged catalytic converter.
• A vacuum restriction to the MAP sensor. Restrictions can cause the EGR flow test to fail due to insufficient MAP changes being monitored during the test.
• An engine that is running poorly may cause this DTC to set.
• Poor connection or damaged harness.
• Harness damage. If the harness appears okay, observe the EGR position sensor display on the scan tool while moving the connectors and the wiring harnesses that are 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 items in mind:

• The PCM will only run the EGR flow test during a gradual deceleration.
• The PCM will only run the EGR test during a closed throttle condition.
• The PCM will only run the EGR test at vehicle speeds above 25 MPH.
• Several deceleration cycles, typically 9-12, will be necessary in order to run a sufficient number of EGR flow test samples.
• The EGR Test Counter displayed on the scan tool can be useful in order to that the EGR flow test is running, and in order to track of the number of test samples taken. The counter will increment each time a test sample is taken.