Initial Inspection and Diagnostic Overview

1. Verify the customer's concern or complaint.
2. Visually inspect the components of the catalyst and exhaust system for the following:
- Exhaust pipes pinched, crushed or rusted through.
- Damaged front exhaust manifold flange covers.
- Damaged Three Way Catalytic Converter (TWC).
- Damaged exhaust inlet pipe/Warm-up Three Way Catalytic Converter (WU-TWC).
- Damaged or rusted heat shields.
- Missing or damaged exhaust hanger insulator.
3. Check engine oil for fuel dilution. Fuel in the engine oil is caused by exhaust blow-by. If the exhaust is restricted, blow-by increases.
4. If all checks are OK, proceed to the Symptom Chart.