Diagnostic Aids

Inspect for the following conditions:

• A restricted EGR pipe.
• An EGR valve that shows signs of excessive heat. Check the exhaust system for a blockage or for a plugged catalytic converter.
• A 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.
• An engine that is running poorly may cause this DTC to set.
• A poor connection or damaged harness. Inspect the wiring harness for 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.

To verify a repair, clear info with the scan tool and run the EGR flow test keeping the following items in mind:

• PCM will only run EGR flow test during a gradual deceleration.
• PCM will only run EGR test during a closed throttle condition.
• PCM will only run EGR test with vehicle speeds at more than 22.9 MPH.
• Several deceleration cycles will be necessary in order to run a sufficient number of EGR flow test samples. A sufficient number of samples is usually 5-15 samples.
• If within the enabling RPM the engine speed drops more than 500 RPM, the PCM will reset the test.
• If within the enabling RPM, the engine speed increases more than 50 RPM, the PCM will reset the test.
• When the PCM commands the EGR valve open, the engine speed will drop. If the engine speed drops below 500 RPM, the test will not run.

If condition is intermittent, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.