Catalytic Converter Replacement - Left Side (LZ9)

Catalytic Converter Replacement - Left Side (LZ9)

Tools Required

J 39194-B Heated Oxygen Sensor Wrench

Removal Procedure

Notice: 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.

Notice: The use of excessive force may damage the threads in the exhaust manifold/pipe.

Important: The in-line connector and louvered end must be kept clear of grease, dirt or other contaminants. Avoid using cleaning solvents of any type. DO NOT drop or roughly handle the HO2S.

Important: The HO2S may be difficult to remove when the engine temperature is less than 48°C (120°F)




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




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




7. Remove the left (front) catalytic converter nuts (1) at the exhaust manifold.
8. Remove the muffler assembly.




9. Remove the lower right heated oxygen sensor HO2S connector position assurance (CPA) retainer (1).
10. Disconnect the rear HO2S electrical connector (2).




11. Remove the lower left HO2S CPA retainer (1).
12. Disconnect the front HO2S electrical connector (2).




13. Remove the lower right and left HO2S (1, 2) using the J 39194-B.




14. Remove the left (front) catalytic converter to right (rear) catalytic converter nuts (3).
15. Remove the right (rear) catalytic converter bolt (5) and nuts (1) at the exhaust manifold.
16. Remove and discard the gasket (6).
17. Remove the right (rear) catalytic converter (2).
18. Remove the left (front) catalytic converter (4).
19. Remove and discard the left (front) catalytic converter to manifold gasket.
20. 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 left (front) catalytic converter studs.
2. Install the left (front) catalytic converter (4).
3. Install a NEW gasket (6) to the right (rear) catalytic converter studs.
4. Install the right (rear) catalytic converter (2).

Notice: Refer to Fastener Notice.

5. Install the right (rear) catalytic converter bolt (5) and nuts (1) at the exhaust manifold.

Tighten the bolt and nuts to 31 N.m (23 lb ft).

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

Tighten the nuts to 31 N.m (23 lb ft).





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 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.

7. If reinstalling the old HO2S, coat the threads with anti-seize compound GM P/N 12377953 or equivalent.
8. Install the lower right and left HO2S (1, 2) using the J 39194-B.

Tighten the sensor to 42 N.m (31 lb ft).




9. Connect the lower left HO2S electrical connector (1).
10. Install the lower left HO2S CPA retainer (2).




11. Connect the lower right HO2S electrical connector (2).
12. Install the lower right HO2S CPA retainer (1).
13. Install the muffler assembly.




14. Install the left (front) catalytic converter nuts (1) at the exhaust manifold.

Tighten the nuts to 31 N.m (23 lb ft).




15. Install the exhaust manifold heat shield.
16. Install the exhaust manifold heat shield bolts.

Tighten the bolts to 10 N.m (89 lb in).




17. Connect the HO2S electrical connector (4).
18. Install the CPA retainer (5).
19. Install the HO2S clip (3) to the oil level indicator tube bracket.
20. Install the air cleaner assembly.
21. Perform the engine mount position adjustment procedure. Refer to Engine Mount Position Adjustment.