Catalytic Converter Replacement - Left Side LY7

Warning: Refer to Exhaust Service Warning in the Preface section.

Warning: Refer to Protective Goggles and Glove Warning in the Preface section.




1. Remove the exhaust manifold heat shield. Refer to Exhaust Manifold Heat Shield Replacement - Left Side.
2. Remove the left catalytic converter to exhaust manifold nuts (1).
3. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.



4. Disconnect the bank 2 sensor 2 heated oxygen sensor (HO2S) electrical connector (3) from the engine wiring harness electrical connector (3).



5. Remove the left catalytic converter (3) to right catalytic converter (1) nuts (2).



6. Remove the left catalytic converter from the vehicle.
7. Discard the catalytic converter to exhaust manifold gasket (2).
8. Discard the left catalytic converter to right catalytic converter gasket (1).

1. Install a NEW catalytic converter seal (2) onto the catalytic converter.
2. Install the catalytic converter to the vehicle.
3. Install a NEW left catalytic converter to right catalytic converter gasket (1).

Caution: Refer to Fastener Caution in the Preface section.




4. Install the left catalytic converter to right catalytic converter nuts (2) and tighten to 25 N·m (18 lb ft).



5. Connect the bank 2 sensor 2 HO2S electrical connector (3) to the engine wiring harness electrical connector (2).



6. Install the left catalytic converter to exhaust manifold nuts (1) and tighten to 45 N·m (33 lb ft).
7. Install the exhaust manifold heat shield. Refer to Exhaust Manifold Heat Shield Replacement - Left Side.
8. Lower the vehicle and inspect for exhaust leaks.

Catalytic Converter Replacement - Left Side LZ4

Special Tools

J 39194-B Heated Oxygen Sensor Wrench

1. Remove the left catalytic converter nuts (1) at the exhaust manifold.
2. Remove the muffler assembly. Refer to Exhaust Muffler Replacement.



3. Remove the rear heated oxygen sensor (HO2S) connector position assurance (CPA) retainer (1).

Note: The HO2S uses a permanently attached pigtail and connector. This pigtail should not be removed from the sensor. Damage or removal of the pigtail or connector will affect proper operation of the sensor.

4. Disconnect the rear HO2S electrical connector (2).



5. Remove the front HO2S CPA retainer (2).

Note: The HO2S uses a permanently attached pigtail and connector. This pigtail should not be removed from the sensor. Damage or removal of the pigtail or connector will affect proper operation of the sensor.

6. Disconnect the front HO2S electrical connector (1).



7. Remove the front and rear HO2S (1, 2) using the J 39194-B .



8. Remove the right catalytic converter bolt (4) and nuts (1) at the exhaust manifold.
9. Remove and discard the gasket (2).
10. Remove the right catalytic converter (3).



11. Remove the left catalytic converter to right catalytic converter nuts (3). (Powertrain shown removed for clarity).
12. Remove the left catalytic converter (1).
13. Remove and discard the left catalytic converter to manifold gasket.
14. Inspect the catalytic converter-to-exhaust manifold flange.

Catalytic Converter to Manifold Flange Warpage:

•	Service Limit: 0.7 mm (0.028 in) max.

•	Standard: 0.7 mm (0.028 in) max.

1. Install a NEW gasket to the front catalytic converter studs.
2. Install the left catalytic converter (1).
3. Install a NEW gasket (2) to the right catalytic converter studs.
4. Install the right catalytic converter (3).

Caution: Refer to Fastener Caution in the Preface section.

5. Install the right catalytic converter bolt (4) and nuts (1) at the exhaust manifold.

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




6. Install the left catalytic converter to right catalytic converter nuts (3). (Powertrain shown removed for clarity).

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




7. Install the front and rear HO2S (1, 2) using the J 39194-B .

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




8. Connect the front HO2S electrical connector (1).
9. Install the front HO2S CPA retainer (2).



10. Disconnect the rear HO2S electrical connector (2).
11. Install the rear HO2S CPA retainer (1).
12. Install the muffler assembly. Refer to Exhaust Muffler Replacement.



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

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

14. Start the engine, and check for exhaust leaks.

Catalytic Converter Replacement - Left Side LZ9

Special Tools

J 39194-B Heated Oxygen Sensor Wrench

1. Remove the air cleaner assembly. Refer to Air Cleaner Assembly Replacement.



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. Refer to Exhaust Muffler Replacement.



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).




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.

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.

Catalytic Converter to Manifold Flange Warpage

•	Service Limit: 0.7 mm (0.028 in) max.

•	Standard: 0.7 mm (0.028 in) max.

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).

Caution: Refer to Fastener Caution in the Preface section.

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

Tighten
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
Tighten the nuts to 31 N·m (23 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.

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
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. Refer to Exhaust Muffler Replacement.



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

Tighten
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
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. Refer to Air Cleaner Assembly Replacement.
21. Perform the engine mount position adjustment procedure. Refer to Engine Mount Position Adjustment.
22. Start the engine, and check for exhaust leaks.