Flow of Diagnosis

1. Verify the customer's concern by operating the exhaust system to duplicate the condition.
2. Inspect to determine if any of the following mechanical or electrical concerns apply.
3. If the inspection reveals an obvious concern that can be readily identified, repair it as required.

Mechanical
- Leaking Fuel Injectors
- Damaged air inlet passages
- Inoperative exhaust gas recirculation (EGR) valve
- Exhaust pipe pinched or crushed
- Damaged or loose vacuum hoses
- The engine oil is diluted with fuel
- Incorrect idle speed
- Dirty air cleaner element
- Damaged air cleaner element

Electrical
- Misrouted or damaged wiring
- Corroded or loose connectors
- Ignition system concern

4. If the concern remains after the inspection, determine the symptom(s) and go to the Symptom Chart. Symptom Related Diagnostic Procedures