Diagnostic Notes

1) VERIFY PROBLEM

NOTE: For catalytic converter and feedback system to function properly, it is essential that vehicle is at operating temperature, (except when attempting to diagnose cold start or cold driveability problem).

2) EXTRACT AND CLEAR FAULT CODES

- Diagnose and repair any fault code related problems before proceeding with further diagnosis.

NOTE: This process verifies that the engine controller and systems are operational.

3) PERFORM VISUAL INSPECTION:

- Engine controller grounds: clean, tight, and in their proper location.
- Vacuum hoses: splits, kinks and proper connections. Check thoroughly for any type of leak or restriction.
- Air leaks at throttle body mounting area and intake manifold sealing surfaces.
- Ignition wires for cracking, harness, proper routing, arcing and carbon tracking.
- Wiring for proper connections, pinches, and cuts.
- Harnesses (EST, ESC, etc...) for proper routing.

4) PROCEED TO DIAGNOSIS BY SYMPTOM

NOTE: These charts contain possible causes of symptoms. Proceed in logical order, easiest to check or most likely cause first.