GM Service Manual Online
For 1990-2009 cars only

Catalytic Converter Replacement 4.2L Engine

Removal Procedure

  1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle .
  2. Remove the heated oxygen sensor (H2OS). Refer to Heated Oxygen Sensor 2 Replacement .

  3. Object Number: 1338717  Size: SH
  4. Remove the nuts that secure the catalytic converter pipe to the exhaust manifold.
  5. Discard the old exhaust seal. Do NOT reuse the seal.

  6. Object Number: 753687  Size: SH
  7. Remove the nuts that secure the catalytic converter pipe to the muffler.
  8. Remove the transmission mount. Refer to Transmission Mount Replacement .
  9. Remove the catalytic converter pipe from the vehicle.

  10. Object Number: 1338721  Size: SH
  11. Remove the exhaust hanger from the catalytic converter pipe.

Installation Procedure


    Object Number: 1338721  Size: SH
  1. Install the exhaust hanger to the catalytic converter pipe.
  2. Install the catalytic converter pipe to the vehicle.
  3. Install the transmission mount. Refer to Transmission Mount Replacement .
  4. Install the converter pipe to the muffler.

  5. Object Number: 753687  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.

    Important: The exhaust flange nuts must be tightened evenly to align the joint and prevent exhaust leaks.

  6. Hand thread both nuts evenly until they contact the exhaust flange.
  7. Tighten
    Tighten the nuts to 45 N·m (33 lb ft).

    Important: Do NOT reuse the old exhaust seal. ALWAYS replace the exhaust seal to prevent exhaust leaks.


    Object Number: 1338717  Size: SH
  8. Install the converter pipe to the exhaust manifold with a NEW exhaust seal.
  9. Hand thread the nuts evenly against the exhaust flange until the pipe is secure.
  10. Tighten
    Tighten the nuts to 50 N·m (37 lb ft).

  11. Install the H2OS. Refer to Heated Oxygen Sensor 2 Replacement .
  12. Lower the vehicle.