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.
Visual Inspection
Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure harness connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and not pinched or cut. If necessary, see appropriate VACUUM DIAGRAMS article to verify routing and connections. Inspect air induction system for possible vacuum leaks or restrictions. Check for air leaks at all intake manifold sealing surfaces. Check ignition wires for cracking, hardness, proper routing and carbon tracking. Ensure PCM and MIL are functioning properly. Ensure there are no DTCs stored, or only intermittent DTCs are present.
After all checks have been performed, verify customer complaint and locate correct symptom. Check items indicated under that symptom. These procedures will normally recommend testing of a specific system or component, such as EGR, ignition, TCC, etc. Go to SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article for appropriate test procedures.
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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.