GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1999 🢒 Catera 🢒 General Information 🢒 General Information 🢒 Catalytic Converter Replacement

Removal Procedure
  1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Remove the pre and post oxygen sensor connectors from the wiring harness.

    3. Object Number: 231131 Size: SH
  3. Remove the exhaust muffler front flange bolts.

    4. Object Number: 231136 Size: SH
  4. Remove the exhaust manifold pipe nuts (1) from the exhaust manifold studs (2) at the exhaust manifold flange.

    5. Object Number: 159595 Size: SH
  5. Remove the catalytic converter support bracket bolts (1) from the catalytic converter support bracket (2).
  6. Remove the catalytic converters from the exhaust manifold flange.

    7. Object Number: 231136 Size: SH
  7. Remove the exhaust manifold pipe gasket (3) from the exhaust manifold if replacement is necessary.
  8. Remove the oxygen sensors from the pipe if replacing the catalytic converters.

Installation Procedure
  1. Install the oxygen sensors into the pipes if previously removed.

    2. Tighten
    Tighten the oxygen sensor to 42 N·m (31 lb ft).


    Object Number: 231131 Size: SH
  2. Install the exhaust manifold pipe gasket (3) to the exhaust manifold.
  3. Install the catalytic converters to the exhaust manifold flange.

    4. Object Number: 159595 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.

  4. Install the catalytic converter support bracket bolts (1) to the catalytic converter support bracket (2).

    5. Tighten
    Tighten the catalytic converter support bracket bolts (1) to 20 N·m (15 lb ft).


    Object Number: 231136 Size: SH
  5. Install the exhaust manifold pipe nuts (1) to the exhaust manifold studs (2) at the exhaust manifold.

    6. Tighten
    Tighten the exhaust manifold pipe nuts (1) to 25 N·m (18 lb ft).


    Object Number: 231131 Size: SH
  6. Install the exhaust muffler front flange nuts.

    7. Tighten
    Tighten the exhaust muffler front flange nuts to 40 N·m (30 lb ft).

  7. Install the pre and post oxygen sensor connectors to the wiring harness.
  8. Check clearances and operate the exhaust system to check for leaks.
  9. Lower the vehicle.