Preliminary Inspection

Check exhaust for corrosion, loose or missing components.
Ensure oxygen sensor is installed properly and pigtail is not contacting hot exhaust or ignition wires.
Check vacuum hoses for splits, kinks and proper routing and connections.
Check for vacuum leaks at throttle body, intake manifold and EGR valve.
Check for proper operation of IAC system.
Check proper operation of PCV system.
Check throttle body inlet screen for damage and/or foreign objects.
Check fuel for excessive water, alcohol, or other contaminates.
Ensure PCM and sensor grounds are clean and tight.
NOTE: To complete a trip cycle for fuel trim diagnostic, fuel trim diagnostic test must be enabled and run according to conditions required to set Code P0171. A trip is not considered complete until fuel trim diagnostics have been run by PCM.