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For 1990-2009 cars only

Catalytic Converter Replacement 4.3L, 4.8L, and 5.3L Engines

Removal Procedure


    Object Number: 665019  Size: SH
  1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle .
  2. If equipped, unclip the oxygen sensor connection from the floor reinforcement.
  3. Disconnect the oxygen sensor electrical connector.

  4. Object Number: 664828  Size: SH
  5. Remove the oxygen sensor clips from the frame.
  6. Disconnect the connector position assurance (CPA) retainers.
  7. Disconnect the oxygen sensor electrical connectors.

  8. Object Number: 664951  Size: SH
  9. Unclip the oxygen sensors electrical connectors from the following:
  10. • Hose clip
    • Transmission crossmember
  11. Disconnect the CPA retainers.
  12. Disconnect the oxygen sensor electrical connectors (1, 2).

  13. Object Number: 858550  Size: SH
  14. Remove the left exhaust manifold pipe nuts.

  15. Object Number: 858553  Size: SH
  16. Remove the right exhaust manifold pipe nuts.

  17. Object Number: 664840  Size: SH
  18. Remove the exhaust muffler nuts.
  19. Remove the catalytic converter.

  20. Object Number: 664954  Size: SH
  21. If necessary, remove the oxygen sensors.

Installation Procedure

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.


    Object Number: 664954  Size: SH
  1. If necessary, install the oxygen sensors.
  2. 1.1. Apply anti-seize compound GM P/N 12377953 or equivalent to the threads of the old oxygen sensors.
    1.2. Install the oxygen sensors.

    Tighten
    Tighten the sensors to 42 N·m (31 lb ft).

  3. Install the catalytic convertor.

  4. Object Number: 858553  Size: SH
  5. Install NEW exhaust manifold pipe seals to the exhaust manifolds.
  6. Install the right exhaust manifold pipe nuts until snug.

  7. Object Number: 858550  Size: SH
  8. Install the left exhaust manifold pipe nuts until snug.
  9. Tighten the exhaust manifold pipe nuts.
  10. Tighten
    Tighten the nuts to 50 N·m (39 lb ft).


    Object Number: 664840  Size: SH
  11. Install the exhaust muffler nuts.
  12. Tighten
    Tighten the nuts to 40 N·m (30 lb ft).


    Object Number: 664951  Size: SH
  13. Connect the oxygen sensor electrical connectors (1, 2).
  14. Connect the CPA retainers.
  15. Clip the oxygen sensors electrical connectors to the following:
  16. • Hose clip
    • Transmission crossmember

    Object Number: 664828  Size: SH
  17. Connect the oxygen sensor electrical connectors.
  18. Connect the CPA retainers.
  19. Install the clip around the engine harness and the oxygen sensor pigtail.

  20. Object Number: 665019  Size: SH
  21. Connect the oxygen sensor electrical connector.
  22. If equipped, clip the oxygen sensor connection to the floor reinforcement.
  23. Lower the vehicle.

Catalytic Converter Replacement 6.0L and 8.1L Engines

Removal Procedure


    Object Number: 647997  Size: SH
  1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle .
  2. Support the transmission with a suitable transmission jack.
  3. Remove the transmission mount to transmission support nuts.
  4. Raise the transmission off of the transmission support.

  5. Object Number: 788013  Size: SH
  6. Remove the transmission support crossmember bolts.
  7. Remove the transmission support crossmember.

  8. Object Number: 665520  Size: SH
  9. Depending on which side is being replaced, perform one of the following steps:
  10. • Remove the exhaust muffler nuts.
    • or
    • Loosen the exhaust pipe clamp.
  11. Remove the necessary exhaust system hangers so that the pipes can be separated.
  12. Use a jack stand to support the exhaust.

  13. Object Number: 665040  Size: SH
  14. Disconnect the connector position assurance (CPA) retainers.
  15. Disconnect the oxygen sensor electrical connectors (1, 2).

  16. Object Number: 858568  Size: SH
  17. Loosen the right exhaust manifold pipe nuts.
  18. Remove the left exhaust manifold pipe nuts.
  19. Using the transmission jack, lower the transmission slightly.

  20. Object Number: 858580  Size: SH
  21. Remove the catalytic converter.
  22. Slide the catalytic converter hanger out of the exhaust pipe hanger bracket.

  23. Object Number: 858597  Size: SH
  24. If equipped with a 6.0L engine, with regular production option (RPO) Y91, remove the catalytic converter.
  25. Slide the catalytic converter hanger out of the exhaust pipe hanger bracket.

  26. Object Number: 664954  Size: SH
  27. Remove the oxygen sensors if the catalytic converter is to be replaced.

Installation Procedure

Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 664954  Size: SH
  1. If the catalytic converter was replaced, perform the following:
  2. 1.1. Apply anti-seize compound GM P/N 12377953 or equivalent to the threads of the old oxygen sensors.
    1.2. Install the oxygen sensors.

    Tighten
    Tighten the sensors to 42 N·m (31 lb ft).


    Object Number: 858597  Size: SH
  3. If equipped with a 6.0L engine, with RPO Y91, install a NEW exhaust seal to the exhaust manifold.
  4. Install the catalytic converter.
  5. Slide the catalytic converter hanger into the exhaust pipe hanger bracket.


    Object Number: 858580  Size: SH
  6. Install a NEW exhaust seal to the exhaust manifold.
  7. Install the catalytic converter.
  8. Slide the catalytic converter hanger into the exhaust pipe hanger bracket.


    Object Number: 858568  Size: SH
  9. Install the left exhaust manifold pipe nuts.
  10. Tighten the right exhaust manifold pipe nuts.
  11. Tighten
    Tighten the nuts to 50 N·m (39 lb ft).

  12. Using the transmission jack, raise the transmission slightly.

  13. Object Number: 665040  Size: SH
  14. Connect the oxygen sensor electrical connectors (1, 2).
  15. Connect the CPA retainers.
  16. Install the exhaust pipe/catalytic converter to the vehicle.
  17. Install the exhaust system hangers.

  18. Object Number: 665520  Size: SH
  19. Depending on which side is being replaced, perform one of the following steps:
  20. • Install the exhaust muffler nuts.

    Tighten
    Tighten the nuts to 40 N·m (30 lb ft).

    • or
    • Install a NEW exhaust pipe clamp.

    Tighten
    Tighten the clamp to 44 N·m (33 lb ft).


    Object Number: 788013  Size: SH
  21. Install the transmission support crossmember.
  22. Install the transmission support crossmember bolts.
  23. Tighten
    Tighten the bolts to 95 N·m (70 lb ft).


    Object Number: 647997  Size: SH
  24. Lower the transmission onto the transmission support.
  25. Install the transmission mount to transmission support nuts.
  26. Tighten
    Tighten the nuts to 40 N·m (30 lb ft).

  27. Remove the support from the transmission.
  28. Lower the vehicle.

Catalytic Converter Replacement 6.6L Engine

Removal Procedure


    Object Number: 647997  Size: SH
  1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Support the transmission with a suitable transmission jack.
  3. Remove the transmission mount to transmission support nuts.
  4. Raise the transmission off of the transmission support.

  5. Object Number: 788013  Size: SH
  6. Remove the transmission support crossmember bolts.
  7. Remove the transmission support crossmember.

  8. Object Number: 694338  Size: SH
  9. If equipped with the 6.6L engine, remove the exhaust muffler nuts.

  10. Object Number: 668379  Size: SH
  11. If equipped with a 6.6L engine, loosen the exhaust pipe clamp.
  12. Slide the exhaust pipe clamp up onto the exhaust pipe adapter.

  13. Object Number: 1284307  Size: SH
  14. If equipped with a 6.6L engine, remove the catalytic converter.
  15. Slide the catalytic converter hanger out of the exhaust pipe hanger bracket.

Installation Procedure


    Object Number: 1284307  Size: SH
  1. If equipped with a 6.6L engine, install the catalytic converter.
  2. Apply water based lubricant to the exhaust pipe hanger bracket, in order to aid in installation.
  3. Slide the catalytic converter hanger into the exhaust pipe hanger bracket.

  4. Object Number: 694338  Size: SH
  5. If equipped with the 6.6L engine, install the exhaust muffler nuts until snug.

  6. Object Number: 668379  Size: SH

    Important: Ensure that the manifold pipe is square to the exhaust pipe adapter.

  7. If equipped with a 6.6L engine, slide the exhaust pipe clamp down and around the pipe connection.
  8. 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.

  9. Tighten the exhaust pipe clamp and muffler nuts.
  10. Tighten

        • Tighten the clamp to 15 N·m (11 lb ft).
        • Tighten the nuts to 40 N·m (30 lb ft).

    Object Number: 647997  Size: SH
  11. Lower the transmission onto the transmission support.
  12. Install the transmission mount to transmission support nuts.
  13. Tighten
    Tighten the bolts to 40 N·m (30 lb ft).

  14. Remove the support from the transmission.
  15. Lower the vehicle.