Preliminary Inspection

• Verify Engine Control Module (ECM), Malfunction Indicator Light (MIL), and CHECK ENGINE are operating correctly, that there are no Diagnostic Trouble Codes (DTCs) stored and scan tool data is within normal operating range. Perform DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L ION article.
• Verify the customer complaint, and locate the correct symptom. Check the items indicated under that symptom.
• Check ECM grounds for clean and tight connection and proper location.
• Check vacuum hoses for splits, kinks, leaks, restrictions and proper connections as shown on Vehicle Emission Control Information label.
• Check for vacuum leaks at the throttle body mounting and intake manifold sealing surfaces.
• Check wiring for proper connections and routing, pinches, burns, cuts or other damage.
• Perform fuel system pressure test. See FUEL SYSTEM DIAGNOSIS under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ION article.
• Perform a careful visual inspection of all systems.

After all checks have been performed, verify customer complaint and locate correct symptom. Check items indicated under that symptom. Not all items listed under each symptom apply to all models and systems. These procedures will normally recommend testing of a specific system or component, such as EGR, ignition, TCC, etc. See SYSTEM & COMPONENT TESTING - 2.2L ION article for test procedures.