GM Service Manual Online
For 1990-2009 cars only

Catalytic Converter Replacement 3100 Engine

Removal Procedure

Important: The three way catalytic converter is serviced by replacing the entire assembly. Always replace the gaskets at the front and rear flanges when servicing the three way catalytic converter. Never reinstall the original gasket.

  1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Disconnect the heated oxygen sensor wiring harness connector and retainers. Refer to Heated Oxygen Sensor Replacement in Engine Controls - 3.1L.
  3. Notice: To prevent internal damage to the flexible coupling of the catalytic converter assembly, the converter must be supported. The vertical movement at the rear of the catalytic converter assembly must not exceed 6 degrees up or down.

  4. Suitably support the exhaust system.

  5. Object Number: 372616  Size: SH
  6. Remove the catalytic converter bolts.
  7. Remove the catalytic converter gasket.

  8. Object Number: 372621  Size: SH
  9. Remove the exhaust manifold pipe stud nuts.
  10. Remove the three way catalytic converter.

  11. Object Number: 107855  Size: SH
  12. Remove the exhaust manifold pipe gasket.

  13. Object Number: 372612  Size: SH
  14. Remove the heated oxygen sensor. Refer to Heated Oxygen Sensor Replacement in Engine Controls - 3.1L.

Installation Procedure


    Object Number: 372612  Size: SH

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  1. Install the heated oxygen sensor. Refer to Heated Oxygen Sensor Replacement in Engine Controls - 3.1L.

  2. Object Number: 107855  Size: SH
  3. Install a new exhaust manifold pipe gasket.

  4. Object Number: 372621  Size: SH

    Notice: To prevent internal damage to the flexible coupling of the catalytic converter assembly, the converter must be supported. The vertical movement at the rear of the catalytic converter assembly must not exceed 6 degrees up or down.

  5. Install and support the three way catalytic converter.
  6. Install the exhaust manifold pipe stud nuts.
  7. Tighten
    Tighten the exhaust manifold pipe stud nuts to 35 N·m (26 lb ft).


    Object Number: 372616  Size: SH
  8. Install the catalytic converter gasket.
  9. Install the catalytic converter bolts.
  10. Tighten
    Tighten the catalytic converter bolts to 45 N·m (33 lb ft).

  11. Remove the support from the exhaust system.
  12. Connect the heated oxygen sensor wiring harness connector and retainers. Refer to Heated Oxygen Sensor Replacement in Engine Controls - 3.1L.
  13. Lower the vehicle.
  14. Inspect the exhaust system for leaks and underbody contact.

Catalytic Converter Replacement 3800 Engine

Removal Procedure

Important: The three way catalytic converter is serviced by replacing the entire assembly. Always replace the gaskets at the front and rear flanges when servicing the three way catalytic converter assembly. Never reinstall the original gasket.

  1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Disconnect the heated oxygen sensor wiring harness connector and retainers. Refer to Heated Oxygen Sensor Replacement in Engine Controls - 3.8L.
  3. Notice: To prevent internal damage to the flexible coupling of the catalytic converter assembly, the converter must be supported. The vertical movement at the rear of the catalytic converter assembly must not exceed 6 degrees up or down.

  4. Suitably support the exhaust system.

  5. Object Number: 372616  Size: SH
  6. Remove the catalytic converter bolts.
  7. Remove the catalytic converter gasket.

  8. Object Number: 372626  Size: SH
  9. Remove the exhaust manifold pipe stud nuts.
  10. Remove the three way catalytic converter.
  11. Remove the exhaust manifold pipe gasket at the exhaust manifold pipe studs.

  12. Object Number: 372612  Size: SH
  13. Remove the heated oxygen sensor. Refer to Heated Oxygen Sensor Replacement in Engine Controls - 3.8L.

Installation Procedure


    Object Number: 372612  Size: SH
  1. Install the heated oxygen sensor. Refer to Heated Oxygen Sensor Replacement in Engine Controls - 3.8L.

  2. Object Number: 372626  Size: SH
  3. Install a new exhaust manifold pipe gasket to the exhaust manifold pipe studs.
  4. Notice: To prevent internal damage to the flexible coupling of the catalytic converter assembly, the converter must be supported. The vertical movement at the rear of the catalytic converter assembly must not exceed 6 degrees up or down.

  5. Install and support the three way catalytic converter.
  6. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  7. Install the exhaust manifold pipe stud nuts.
  8. Tighten
    Tighten the exhaust manifold pipe stud nuts to 35 N·m (26 lb ft).


    Object Number: 372616  Size: SH
  9. Install the catalytic converter gasket.
  10. Install the catalytic converter bolts.
  11. Tighten
    Tighten the catalytic converter bolts to 45 N·m (33 lb ft).

  12. Connect the heated oxygen sensor wiring harness connector and retainers. Refer to Heated Oxygen Sensor Replacement in Engine Controls - 3.8L.
  13. Remove the support from the exhaust system.
  14. Lower the vehicle.
  15. Inspect the exhaust system for leaks and underbody contact.