GM Service Manual Online
For 1990-2009 cars only

Catalytic Converter Replacement - Left Side LA3, LY9

Removal Procedure

Caution: Refer to Exhaust Service Caution in the Preface section.

Caution: Refer to Protective Goggles and Glove Caution in the Preface section.

  1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.

  2. Object Number: 785791  Size: SH
  3. Disconnect the Heated oxygen sensor at the sensor pigtail.
  4. Remove the heated oxygen sensor if replacement is necessary. Refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 in Engine Controls-2.6L and 3.2L.

  5. Object Number: 772367  Size: SH
  6. Remove the nuts securing the exhaust pipe to the left catalytic converter.

  7. Object Number: 786652  Size: SH
  8. Remove the nuts securing the exhaust pipe to the right catalytic converter.
  9. Notice: Refer to Flex Decoupler Notice in the Preface section.

  10. Position the exhaust system rearward, enough to allow the studs located in the rear of the catalytic converters to clear the exhaust pipe flange.
  11. Allow the exhaust system to rest on the floor panel tunnel brace.

  12. Remove the left side catalytic converter seal. Do not reuse the seal.
  13. Remove the right side catalytic converter gasket. Do not reuse the gasket.

  14. Object Number: 772363  Size: SH
  15. Remove the 2 nuts attaching the catalytic converter to the catalytic converter hanger bracket.
  16. Remove the 3 nuts attaching the catalytic converter to the exhaust manifold.
  17. Remove the catalytic converter and the seal. Do not reuse the seal.

Installation Procedure


    Object Number: 772363  Size: SH
  1. Insert a NEW seal into the seal grove of the catalytic converter.
  2. Notice: Refer to Exhaust System Inspection Notice in the Preface section.

  3. Position the catalytic converter to the exhaust manifold and catalytic converter hanger bracket.
  4. Notice: Refer to Fastener Notice in the Preface section.

  5. Install the 3 nuts attaching the catalytic converter to the exhaust manifold.
  6. Tighten
    Tighten the exhaust manifold pipe nuts to 25 N·m (18 lb ft).

  7. Install the 2 nuts attaching the catalytic converter to the catalytic converter hanger bracket.
  8. Tighten
    Tighten the catalytic converter hanger bracket nuts to 25 N·m (18 lb ft).


    Object Number: 772367  Size: SH
  9. Place a NEW seal on the left side catalytic converter flange.
  10. Place a NEW gasket over the right side catalytic converter studs.
  11. Align the exhaust pipe flanges with the studs located in the rear of the catalytic converters.
  12. Install the 2 nuts securing the exhaust pipe to the left catalytic converter.
  13. Tighten
    Tighten the catalytic converter nuts to 15 N·m (11 lb ft).

    Notice: Refer to Flex Decoupler Notice in the Preface section.


    Object Number: 786652  Size: SH
  14. Install the 2 nuts securing the exhaust pipe to the right catalytic converter.
  15. Tighten
    Tighten the catalytic converter nuts to 15 N·m (11 lb ft).

  16. Install the heated oxygen sensor if previously removed. Refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 in Engine Controls-2.6L and 3.2L.

  17. Object Number: 785791  Size: SH
  18. Connect the Heated oxygen sensor at the sensor pigtail.
  19. Lower the vehicle.

Catalytic Converter Replacement - Left Side LY7

Removal Procedure

Caution: Refer to Exhaust Service Caution in the Preface section.

Caution: Refer to Protective Goggles and Glove Caution in the Preface section.

  1. Remove the left bank exhaust manifold heat shield. Refer to Exhaust Manifold Heat Shield Replacement - Left Side .

  2. Object Number: 1221180  Size: SH
  3. Remove the catalytic converter nuts.
  4. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
  5. Disconnect the oxygen sensor electrical connector.

  6. Object Number: 1224063  Size: SH
  7. Disconnect the muffler pipe from the left and right side catalytic converters.
  8. Remove the exhaust pipe to right bank catalytic converter fasteners.
  9. Carefully remove the catalytic converter with the seal/heat shield and oxygen sensor from the exhaust manifold.
  10. Remove the oxygen sensor from the catalytic converter. Refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 .

Installation Procedure

  1. Install the oxygen sensor to the catalytic converter. Refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 .
  2. Important: Inspect the catalytic converter seal/heat shield sealing surface. Replace the seal/heat shield if the sealing surface is worn or damaged.

  3. Install the catalytic converter seal/heat shield to the catalytic converter.

  4. Object Number: 1221180  Size: SH
  5. Carefully install the catalytic converter to the exhaust manifold.
  6. Install the catalytic converter nuts.
  7. Connect the oxygen sensor electrical connector.
  8. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 1224063  Size: SH

    Important: Inspect the catalytic converter seals. Replace the seals if they are worn or damaged.

  9. Connect the muffler pipes to the left and right side catalytic converters.
  10. Tighten
    Tighten the muffler nuts to 22 N·m (16 lb ft).

  11. Lower the vehicle.
  12. Tighten the catalytic converter to exhaust manifold fasteners.
  13. Tighten
    Tighten the catalytic converter nuts to 50 N·m (37 lb ft).

  14. Install the right bank exhaust manifold heat shield. Refer to Exhaust Manifold Heat Shield Replacement - Left Side .

Catalytic Converter Replacement - Left Side LS6

Removal Procedure

Caution: Refer to Exhaust Service Caution in the Preface section.

Caution: Refer to Protective Goggles and Glove Caution in the Preface section.


    Object Number: 772383  Size: SH
  1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Support the exhaust with a suitable screw jack.
  3. Remove the floor panel tunnel brace. Refer to Exhaust System Replacement .

  4. Object Number: 1455615  Size: SH
  5. Disconnect the exhaust system from the left and right side catalytic converters. Refer to Exhaust System Replacement .
  6. Using the screw jack, lower the exhaust system
  7. Disconnect the oxygen sensor electrical connectors.
  8. Remove the left bank catalytic converter to exhaust manifold nuts.
  9. Carefully remove the catalytic converter with the gasket (1) and oxygen sensors from the exhaust manifold.
  10. Remove the oxygen sensors from the catalytic converter. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 and Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 in Engine Controls - 5.7L.

Installation Procedure

  1. Install the oxygen sensors to the catalytic converter. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 and Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 in Engine Controls - 5.7L.
  2. Install the catalytic converter gasket (1) to the catalytic converter.

  3. Object Number: 1455615  Size: SH
  4. Carefully install the catalytic converter to the exhaust manifold.
  5. Install the catalytic converter nuts.
  6. Tighten the catalytic converter to exhaust manifold nuts.
  7. Tighten
    Tighten the catalytic converter nuts to 50 N·m (37 lb ft).

  8. Connect the oxygen sensor electrical connectors.
  9. Using the screw jack, raise the exhaust system.
  10. Connect the exhaust system to the left and right side catalytic converters. Refer to Exhaust System Replacement .

  11. Object Number: 772383  Size: SH
  12. Remove the screw jack.
  13. Install the floor panel tunnel brace. Refer to Exhaust System Replacement .
  14. Lower the vehicle.