Symptom Troubleshooting (Engine Performance): 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 the following flowchart:
- If a DTC exists, diagnose the applicable DTC inspection. (See DTC TABLE ).
- If no DTC exists and the MIL does not illuminate or flash, diagnose the applicable symptom troubleshooting. (See QUICK DIAGNOSTIC CHART ).
  
  Fig 1: Malfunction Indicator Lamp (MIL) Diagnostic Flow Chart
  Courtesy of MAZDA MOTORS CORP.