GM Service Manual Online
For 1990-2009 cars only

Removal Procedure

  1. Raise the vehicle. Support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Remove the Heated Oxygen Sensor 2 (HO2S2). Refer to Heated Oxygen Sensor 2 Replacement in Engine Controls.

  3. Object Number: 235649  Size: SH
  4. Remove the 1 bolt and the clamp (3) securing the front pipe to the Three-Way Catalytic Converter (TWC).
  5. Remove the 2 bolts securing the Three-Way Catalytic Converter (TWC) to the muffler/tail pipe assembly .

  6. Remove the hangers from the rear of the TWC.
  7. Remove the TWC from the vehicle.
  8. Clean the gasket and seal mating surfaces.

Installation Procedure


    Object Number: 235662  Size: SH
  1. Connect the Three-Way Catalytic Converter (TWC) (1) to the vehicle. Secure the front of the TWC with the clamp and 1 bolt. Secure the rear of the TWC with 2 hangers (2).
  2. Install the 2 bolts in order to secure the TWC to the muffler/tail pipe assembly. Finger tighten the bolts.
  3. 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.

  4. Align all system components properly in order to prevent any noise or vibrations before tightening the fasteners.
  5. Tighten

        • Tighten the front pipe-to-TWC clamp bolt to 50 N·m (37 lb ft).
        • Tighten the TWC-to-muffler/tail pipe assembly bolts to 50 N·m (37 lb ft).
  6. Install the Heated Oxygen Sensor 2 (HO2S2). Refer to Heated Oxygen Sensor 2 Replacement in Engine Controls.
  7. Lower the vehicle.