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. Object Number: 235649  Size: SH
  3. Remove the Heated Oxygen Sensor 1 (2). Refer to Heated Oxygen Sensor 1 Replacement in Engine Controls.
  4. Remove the following components from the exhaust manifold:

    • The 2 bolts
    • The 2 springs
  5. Remove the 1 bolt and the clamp (3) which secures the front pipe to the Three Way Catalytic Converter (TWC). Remove the front pipe from the vehicle.
  6. Clean the gasket and seal the mating surfaces.

Installation Procedure


    Object Number: 235649  Size: SH
  1. Install the front pipe (4) with the new gasket to the vehicle. Secure the front pipe (4) to the manifold with 2 springs and 2 bolts. Finger tighten the bolts.
  2. Install the front pipe with the new seal to the Three Way Catalytic Converter (TWC). Secure the front pipe with 1 bolt and clamp. Finger tighten the bolt.
  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-exhaust manifold bolts to 50 N·m (37 lb ft).
        • Tighten the front pipe-to-TWC Clamp bolt to 50 N·m (37 lb ft).
  6. Install the Heated Oxygen Sensor 1 (2). Refer to Heated Oxygen Sensor 1 Replacement in Engine Controls.
  7. Lower the vehicle.