Tools Required

J 39194-B Heated Oxygen Sensor Socket

1. Remove the air intake duct. Refer to Air Cleaner Inlet Duct Replacement in Engine Controls - 3.5L (LX9).
2. Remove the connector position assurance (CPA) retainer (2).
3. Disconnect the heated oxygen sensor (HO2S) electrical connector (1).

Important: 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. Remove the HO2S using the J 39194-B .



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



6. Remove the upper exhaust manifold nuts.
7. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
8. Remove the front catalytic converter. Refer to Catalytic Converter Replacement .
9. Remove the lower exhaust manifold nuts.
10. Remove the exhaust manifold.
11. Remove and discard the exhaust manifold gasket.

1. Install a NEW exhaust manifold gasket onto the cylinder head studs.
2. Install the exhaust manifold.

Notice: Refer to Fastener Notice in the Preface section.

3. Install the exhaust manifold nuts.

Tighten
Tighten the nuts to 16 N·m (12 lb ft).

4. Install the front catalytic converter. Refer to Catalytic Converter Replacement .



5. Install the exhaust manifold heat shield and bolts.

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





Important: Whenever the oxygen sensor is removed, coat the threads with nickel-based anti-seize compound, such as GM P/N 5613695, or equivalent.

6. Install the HO2S using J 39194-B .

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

7. Connect the HO2S electrical connector (1).
8. Install the CPA retainer (2).
9. Ensure that the connector rosebud is attached to the clip.
10. Install the air intake duct. Refer to Air Cleaner Inlet Duct Replacement in Engine Controls - 3.5L (LX9).