Catalytic Converter Replacement 4.8L,5.3L

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. Remove the transmission support crossmember bolts and nuts.
6. Remove the transmission support crossmember.



7. Remove the clip from around the engine harness and the oxygen sensor pigtail.
8. Disconnect the connector position assurance (CPA) retainers.
9. Disconnect the oxygen sensor electrical connectors.



10. Unclip the oxygen sensor electrical connectors from the following:

•

Hose clip

•	Transmission crossmember

11. Disconnect the CPA retainers.
12. Disconnect the oxygen sensor electrical connectors (1, 2).



13. Remove the left exhaust manifold pipe nuts.



14. Remove the right exhaust manifold pipe nuts.



15. Remove the exhaust muffler nuts.
16. Remove the catalytic converter.



17. Remove the oxygen sensors if the catalytic converter is to be replaced.

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.

1. If the catalytic converter was replaced, perform the following:

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 oxygen sensors to 42 N·m (31 lb ft).

2. Install the catalytic convertor.



3. Install NEW exhaust manifold pipe seals to the exhaust manifolds.
4. Install the right exhaust manifold pipe nuts until sung.



5. Install the left exhaust manifold pipe nuts until snug.
6. Tighten the right and left exhaust manifold pipe nuts.

Tighten
Tighten the nuts to 50 N·m (39 lb ft).




7. Install the exhaust muffler nuts.

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




8. Connect the oxygen sensor electrical connectors (1, 2).
9. Connect the CPA retainers.
10. Clip the oxygen sensors electrical connectors to the following:

•

Hose clip

•	Transmission crossmember




11. Connect the oxygen sensor electrical connectors.
12. Connect the CPA retainers.
13. Install the clip around the engine harness and the oxygen sensor pigtail.



14. Install the transmission support crossmember.
15. Install the transmission support crossmember bolts and nuts.

Tighten
Tighten the bolts to 95 N·m (70 lb ft).




16. lower the transmission onto the transmission support.
17. Install the transmission mount to transmission support nuts.

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

18. Remove the transmission jack.
19. Lower the vehicle.

Catalytic Converter Replacement 6.0L and 8.1L Engines

1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
2. Remove the muffler. Refer to Muffler Replacement .
3. Disconnect the connector position assurance (CPA) retainers.
4. Disconnect the oxygen sensor electrical connectors (1, 2).



5. Remove the left exhaust manifold pipe nuts.



6. Remove the catalytic converter.
7. Slide the catalytic converter hanger out of the exhaust pipe hanger bracket.



8. Remove the oxygen sensors if the catalytic converter is to be replaced.

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.

1. If the catalytic converter was replaced, perform the following:

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).




2. Install a NEW exhaust seal to the exhaust manifold.
3. Install the catalytic converter.

Slide the catalytic converter hanger into the exhaust pipe hanger bracket.




4. Install the left exhaust manifold pipe nuts.

Tighten
Tighten the nuts to 50 N·m (39 lb ft).




5. Connect the oxygen sensor electrical connectors (1, 2).
6. Connect the CPA retainers.
7. Install the muffler. Refer to Muffler Replacement .
8. Lower the vehicle.