Emission Control Systems: Testing and Inspection

The technician should be aware that diagnosis and testing of the Emission Control System should begin at the Powertrain Management System level, where testing begins with Diagnosis by Symptom, and is narrowed to testing of a "specific" subsystem and it's related wiring and components. Following the appropriate diagnostic routines may prevent misdiagnosis and unnecessary component replacement. Refer to Powertrain Management/Testing and Inspection/Procedures.