Catalytic Converter Replacement LS4

Important: 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 gaskets.

1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
2. Disconnect the heated oxygen sensor (HO2S) electrical connector.



3. Remove the catalytic converter pipe stud nuts (2).



4. Remove the catalytic converter nuts (3).
5. Using a suitable adjustable jack, loosely support the exhaust system.



6. Remove the catalytic converter hangers (1) from the converter.
7. Remove the catalytic converter.
8. Remove and discard the catalytic converter gaskets.



9. Remove the HO2S, if required.
10. Clean and inspect the exhaust manifold and the exhaust pipe mating surfaces.

Notice: To prevent internal damage to the flexible coupling of the catalytic converter assembly, the converter must be supported. The vertical movement at the rear of the catalytic converter assembly must not exceed 6 degrees up or down.

1. Install the HO2S, if required.



2. Install NEW gaskets to the exhaust manifold and muffler studs.
3. Position the catalytic converter into place.
4. Install the catalytic converter hangers (1) to the converter.

Notice: Refer to Fastener Notice in the Preface section.




5. Install the catalytic converter pipe stud nuts (2).

Tighten
Tighten the nuts to 35 N·m (26 lb ft).




6. Install the catalytic converter nuts (3).

Tighten
Tighten the nuts to 60 N·m (44 lb ft).

7. Remove the exhaust system support.



8. Connect the HO2S electrical connector.
9. Lower the vehicle.
10. Run the vehicle and inspect the exhaust system for leaks and underbody contact.

Catalytic Converter Replacement V6

Important: 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.

1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.
2. Disconnect the heated oxygen sensor (HO2S) electrical connector.
3. Remove the exhaust manifold pipe stud nuts (2).
4. Remove the exhaust manifold pipe gasket (1).
5. Support the exhaust system.



6. Remove the catalytic converter nuts.



7. Remove the catalytic converter hangers.
8. Remove the catalytic converter.
9. Remove the catalytic converter gasket.
10. Clean and inspect the exhaust manifold and the exhaust pipe gasket mating surfaces.
11. Remove the HO2S, if required. Refer to Heated Oxygen Sensor 2 Replacement.

1. Install the HO2S, if required. Refer to Heated Oxygen Sensor 2 Replacement.

Notice: To prevent internal damage to the flexible coupling of the catalytic converter assembly, the converter must be supported. The vertical movement at the rear of the catalytic converter assembly must not exceed 6 degrees up or down.

2. Install a new gasket to the exhaust pipe studs.
3. Install and support the catalytic converter.

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 nuts.

Tighten
Tighten the nuts to 60 N·m (44 lb ft).




5. Install a new exhaust manifold pipe gasket (1).
6. Install the exhaust manifold pipe stud nuts (2).

Tighten
Tighten the nuts to 35 N·m (26 lb ft).




7. Install the catalytic converter hangers.
8. Remove the support from the exhaust system.
9. Connect the HO2S electrical connector.
10. Lower the vehicle.
11. Inspect the exhaust system for leaks and possible underbody contact.