On-Board Diagnostic (Engine Control System AJ]: Foreword

When the customer reports a vehicle malfunction, check the malfunction indicator lamp (MIL) indication and diagnostic trouble code (DTC), then diagnose the malfunction according to following flowchart.
- If the DTC exists, diagnose the applicable DTC inspection. (See DTC TABLE .)
- If the DTC does not exist and the MIL does not illuminate or flash, diagnose the applicable symptom troubleshooting. (See SYMPTOM DIAGNOSTIC INDEX .)
Fig 1: Identifying Malfunction Flowchart
Courtesy of MAZDA MOTORS CORP.