Diagnostic Aids

PCM will only run EGR flow test during gradual deceleration, a closed throttle condition and with vehicle speed greater than 25 MPH. Accelerate vehicle to greater than 25 MPH, and gradually decelerate 9-12 times.

Check for faulty connections or damaged harness. Inspect PCM harness connector EGR control circuit for backed-out terminal. Observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

If EGR valve shows signs of excessive heat, check exhaust system for blockage or plugged catalytic converter.