GM Service Manual Online
For 1990-2009 cars only

Catalytic Converter Replacement - Left Side LZ4

Removal Procedure

Note: 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 install the original gasket.


    Object Number: 1886075  Size: SH
  1. Remove the heated oxygen sensors (HO2S). Refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 2.
  2. Lower the vehicle.
  3. Remove the left side exhaust manifold heat shield bolts (1).
  4. Remove the left side exhaust manifold heat shield.

  5. Object Number: 1886091  Size: SH
  6. Remove the left side catalytic converter to exhaust manifold nuts (1).
  7. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.
  8. Support the exhaust system.

  9. Object Number: 1886121  Size: SH
  10. Remove the catalytic converter to muffler nuts (1).
  11. Reposition the muffler assembly rearward until the catalytic converter can be removed.
  12. Remove the catalytic converter.
  13. Remove the catalytic converter gaskets.
  14. Clean and inspect the exhaust manifold and the exhaust pipe gasket mating surfaces.

Installation Procedure


    Object Number: 1886121  Size: SH
  1. Install the catalytic converter gasket onto the catalytic converter.
  2. Reposition the muffler assembly rearward until the catalytic converter can be installed.
  3. Install the catalytic converter.
  4. Caution: Refer to Fastener Caution in the Preface section.

  5. Install the catalytic converter nuts (1) and tighten to 60 N·m (44 lb ft).
  6. Remove the support from the exhaust system.

  7. Object Number: 1886091  Size: SH
  8. Lower the vehicle.
  9. Install the left side catalytic converter to exhaust manifold nuts (1) and tighten to 35 N·m (26 lb ft).

  10. Object Number: 1886075  Size: SH
  11. Install the exhaust manifold heat shield.
  12. Install the left side exhaust manifold heat shield bolts (1) and tighten to 10 N·m (89 lb in).
  13. Install the HO2S sensor. Refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 2.

Catalytic Converter Replacement - Left Side LY7 or LCS

Removal Procedure

Note: 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 install the original gasket.


    Object Number: 1888717  Size: SH
  1. Remove the heated oxygen sensor (HO2S). Refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 2.
  2. Lower the vehicle.
  3. Disconnect the oxygen sensor electrical connector (1).

  4. Object Number: 1888891  Size: SH
  5. Remove the left side exhaust manifold heat shield bolts (1).
  6. Remove the left side exhaust manifold heat shield.

  7. Object Number: 1888899  Size: SH
  8. Remove the left side catalytic converter to exhaust manifold nuts (1).
  9. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.
  10. Support the exhaust system.

  11. Object Number: 1886121  Size: SH
  12. Remove the catalytic converter to muffler nuts (1).
  13. Reposition the muffler assembly rearward until the catalytic converter can be removed.
  14. Remove the catalytic converter.
  15. Remove the catalytic converter gaskets.
  16. Clean and inspect the exhaust manifold and the exhaust pipe gasket mating surfaces.

Installation Procedure


    Object Number: 1886121  Size: SH
  1. Install the catalytic converter gasket onto the catalytic converter.
  2. Reposition the muffler assembly rearward until the catalytic converter can be installed.
  3. Install the catalytic converter.
  4. Caution: Refer to Fastener Caution in the Preface section.

  5. Install the catalytic converter nuts (1) and tighten to 60 N·m (44 lb ft).
  6. Remove the support from the exhaust system.

  7. Object Number: 1888891  Size: SH
  8. Lower the vehicle.
  9. Install the left side catalytic converter to exhaust manifold nuts (1) and tighten to 35 N·m (26 lb ft).

  10. Object Number: 1888891  Size: SH
  11. Install the exhaust manifold heat shield.
  12. Install the left side exhaust manifold heat shield bolts (1) and tighten to 10 N·m (89 lb in).

  13. Object Number: 1888717  Size: SH
  14. Disconnect the oxygen sensor electrical connector (1) and tighten to .
  15. Install the HO2S sensor. Refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 2.