Catalytic Converter: Service and Repair

Catalytic Converter Replacement (LS4) (5.3L)

Removal Procedure

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 Service and Repair
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.



Installation Procedure

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 Fastener Caution

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

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





6. Install the catalytic converter nuts (3).

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.