Catalytic Converter: Service and Repair

Catalytic Converter Replacement (5.3L Engine)

Removal Procedure
1. Raise and suitably support the vehicle. Refer to Vehicle Lifting.







NOTICE: Refer to Heated Oxygen and Oxygen Sensor Notice in Service Precautions.
Heated Oxygen and Oxygen Sensor Notice

NOTICE: Refer to Excessive Force and Oxygen Sensor Notice in Service Precautions.
Excessive Force and Oxygen Sensor Notice

2. Unscrew both front Heated Oxygen Sensor (H02S) sensors (1) from the catalytic converter.
3. Unscrew both rear H02S sensors (2) from the catalytic converter.
4. Remove the transmission support.
5. Remove the rear propeller shaft.
6. If equipped with four wheel drive (4WD), unbolt the front propeller shaft from the drive axle.
7. Place the propeller shaft on top of the pinion yoke.







8. Remove the exhaust muffler nuts.







9. Remove the left exhaust manifold pipe nuts.







10. Remove the right exhaust manifold pipe nuts.
11. Raise the transmission.







12. Remove the catalytic converter (1) by angling the outlet pipe toward the left side of the vehicle to gain the necessary clearance for removal.



Installation Procedure







1. Install the catalytic converter (1) in reverse order of removal by starting with the outlet pipe angled toward the left side of the vehicle.







2. Install the exhaust muffler nuts. Position the catalytic converter in the installed location before tightening the nuts.
Tighten the nuts to 45 Nm (33 ft. lbs.).







3. Install the right exhaust manifold pipe nuts. Position the catalytic converter in the installed location before tightening the nuts.
Tighten the nuts to 50 Nm (37 ft. lbs.).







4. Install the left exhaust manifold pipe nuts.
Tighten the nuts to 50 Nm (37 ft. lbs.).

5. If equipped with 4WD, install the front propeller shaft to the drive axle.
6. Install the rear propeller shaft.
7. Lower the transmission.
8. Install the transmission support.


Important: A special anti-seize compound is used on the HO2S threads. The compound consists of liquid graphite and glass beads. The graphite tends to burn away, but the glass beads remain, making the sensor easier to remove. New, or service replacement sensors already have the compound applied to the threads. If the sensor is removed from an exhaust component and if for any reason the sensor is to be reinstalled, the threads have anti-seize compound applied before the reinstallation.

9. If reinstalling the old sensors, coat the threads with anti-seize compound GM P/N 12377953, or equivalent.







NOTICE: Refer to Component Fastener Tightening Notice in Service Precautions.
Fastener Notice

Important: If the HO2S sensor is connected to the main wiring harness during installation. Rotate the HO2S sensor several turns counterclockwise before threading the HO2S sensor into the catalytic converter. This action of initially reverse winding of the pigtail wires will prevent a condition where the HO2S sensor pigtail wires become severely twisted or binding once the HO2S sensor is installed into the catalytic converter.

10. Install both front HO2S sensors (1) to the catalytic converter.
Tighten the sensor to 42 Nm (31 ft. lbs.).

11. Install both rear HO2S (2) to the catalytic converter.
Tighten the sensor to 42 Nm (31 ft. lbs.).