Catalytic Converter Replacement - Right Side (MT2)

Catalytic Converter Replacement - Right Side (LZ9 w/RPO MT2)

Special Tools

J 39194-B Heated Oxygen Sensor Wrench

Removal Procedure




1. Remove the connector position assurance (CPA) retainer (5).
2. Disconnect the engine harness electrical connector (4) from the heated oxygen sensor (HO2S).
3. Remove the HO2S clip (3) from the oil level indicator tube bracket.




4. Remove the exhaust manifold heat shield bolts.
5. Remove the exhaust manifold heat shield.




6. Remove the right (rear) catalytic converter nuts (1).




7. Remove the muffler assembly. Refer to Exhaust Muffler Replacement (LE5 or LE9 With MH8) Exhaust Muffler ReplacementExhaust Muffler Replacement (2.4L, 3.5L, and 3.9L) Exhaust Muffler ReplacementExhaust Muffler Replacement (LY7, LZ9) Exhaust Muffler Replacement.
8. Remove the rear stabilizer shaft. Refer to Stabilizer Shaft Replacement Rear Suspension.
9. Remove the connector position assurance (CPA) retainer (1).
10. Disconnect the HO2S electrical connector (2).





Caution: The oxygen sensor uses a permanently attached pigtail and connector. Do not remove the pigtail from the oxygen sensor. Damage to or removal of the pigtail connector could affect proper operation of the oxygen sensor.

11. Remove the HO2S (2) using the J 39194-B .




12. Remove the left (front) catalytic converter to right (rear) catalytic converter nuts (2).
13. Remove the right (rear) catalytic converter (1).
14. Remove and discard the gasket.
15. Inspect the catalytic converter-to-exhaust manifold flange.

* Service Limit: 0.7 mm (0.028 in) max.
* Standard: 0.7 mm (0.028 in) max.

Installation Procedure




1. Install a NEW gasket to the catalytic converter studs.
2. Install the right (rear) catalytic converter (1).

Caution: Refer to Fastener Caution Fastener Caution.

3. Install the left (front) catalytic converter to right (rear) catalytic converter nuts (2).

Tighten the nuts to 22 Nm (16 lb ft).





Note: 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 beads remain, making the sensor easier the 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 must be have anti-seize compound applied before the reinstallation.

4. If reinstalling the old HO2S, coat the threads with anti-seize compound GM P/N 12377953 or equivalent.
5. Install the HO2S (2) using the J 39194-B .

Tighten the sensor to 42 Nm (31 lb ft).

6. Lower the vehicle to the ground, start the engine, and check for exhaust leaks.




7. Connect the HO2S electrical connector (2).
8. Install the CPA retainer (1).
9. Install the muffler assembly. Refer to Exhaust Muffler Replacement (LE5 or LE9 With MH8) Exhaust Muffler ReplacementExhaust Muffler Replacement (2.4L, 3.5L, and 3.9L) Exhaust Muffler ReplacementExhaust Muffler Replacement (LY7, LZ9) Exhaust Muffler Replacement.
10. Install the rear stabilizer shaft. Refer to Stabilizer Shaft Replacement Rear Suspension.




11. Install the right (rear) catalytic converter nuts (1).

Tighten the nuts to 45 Nm (33 lb ft).




12. Install the exhaust manifold heat shield.
13. Install the exhaust manifold heat shield bolts.

Tighten the bolts to 10 Nm (89 lb in).




14. Connect the engine harness electrical connector (4) to the HO2S.
15. Install the CPA retainer (5).
16. Install the HO2S clip (3) to the oil level indicator tube bracket.
17. Perform the engine mount position adjustment procedure. Refer to Engine Mount Position Adjustment .
18. Start the engine, and check for exhaust leaks.