Engine Controls - Tests W/Codes: Introduction: Notes

If no faults were found while performing basic diagnostic procedures in the BASIC TESTING article, proceed with self-diagnostics. If no fault codes or only pass codes are present after entering self-diagnostics, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).

The self-diagnostic system can be accessed using an OBD-II compliant scan tool or using Malfunction Indicator Light (MIL) if an OBD-II type scan tool is not available. The 2 methods differ greatly, procedures and DTCs cannot be interchanged.