Diagnostic Aids

PCM will only run EGR flow test during gradual deceleration, a closed throttle condition and with vehicle speed greater than 20 MPH. Accelerate vehicle to greater than 20 MPH, and gradually decelerate 9-13 times. Check for faulty connections or damaged harness. Inspect PCM harness connector EGR control circuit for backed-out terminal. Observe ACTUAL EGR POSITION display on scan tool while moving all related harnesses 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. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.