Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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 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.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.