GM Service Manual Online
For 1990-2009 cars only

Catalytic Converter Replacement with Exhaust Manifold Pipe Nuts

Removal Procedure

The catalytic converter is serviced by replacing the entire assembly. Always replace the gasket at the rear flange when servicing the 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. 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.

  3. Suitably support the exhaust system.

  4. Object Number: 389538  Size: SH
  5. Remove the catalytic converter bolts.
  6. Remove the catalytic converter gasket.

  7. Object Number: 620039  Size: SH
  8. Remove the exhaust manifold pipe stud nuts.
  9. Remove the catalytic converter.
  10. Remove the exhaust manifold pipe seal.
  11. Inspect the seal. Replace as necessary.

Installation Procedure


    Object Number: 620039  Size: SH
  1. Install the exhaust manifold pipe seal.
  2. 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.

  3. Install and support the catalytic converter.
  4. 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.

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


    Object Number: 389538  Size: SH
  7. Install the catalytic converter gasket.
  8. Install the catalytic converter bolts.
  9. Tighten
    Tighten the catalytic converter bolts to 45 N·m (33 lb ft).

  10. Remove the support from the exhaust system.
  11. Inspect for leaks and underbody contact.
  12. Lower the vehicle.

Catalytic Converter Replacement with Exhaust Manifold Bolts

Removal Procedure

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

  1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. 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.

  3. Suitably support the exhaust system.

  4. Object Number: 620042  Size: SH
  5. Remove the catalytic converter bolts.
  6. Remove the catalytic converter gasket.

  7. Object Number: 617101  Size: SH
  8. Remove the exhaust manifold pipe bolts.
  9. Remove the catalytic converter.

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

Installation Procedure


    Object Number: 620006  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. If the replacement catalytic converter has an oxygen sensor opening, install a oxygen sensor plug.
  2. Tighten
    Tighten the oxygen sensor plug to 42 N·m (31 lb ft).


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

  4. Object Number: 617101  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 catalytic converter.
  6. Install the exhaust manifold pipe bolts.
  7. Tighten
    Tighten the exhaust manifold pipe bolts to 35 N·m (26 lb ft).


    Object Number: 620042  Size: SH
  8. Install a new 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. Inspect for leaks and underbody contact.
  13. Lower the vehicle.