For 1990-2009 cars

### Removal Procedure

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 oil level indicator. Refer to Oil Level Indicator and Tube Replacement.
3. Remove the catalytic converter. Refer to Catalytic Converter Replacement - Left Side.
4. Remove the exhaust manifold bolts (1).

Note: Do not reuse the gasket.

5. Remove the exhaust manifold and gasket. Discard the gasket.
6. Remove the heated oxygen sensor (1) from the exhaust manifold.

### Installation Procedure

Note: A special anti-seize compound is used in 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 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 have anti-seize compound applied before the reinstallation.

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

Caution: Refer to Fastener Caution in the Preface section.

2. Install the HO2S (1) to the exhaust manifold.

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

3. Install one exhaust manifold bolt (1) to the exhaust manifold.
4. Install the NEW exhaust manifold gasket onto the exhaust manifold and bolt.
5. Install the exhaust manifold (with gasket) to the cylinder head and the catalytic converter.
6. Install the remaining exhaust manifold bolts.

Tighten
Tighten the bolts to 20 N·m (15 lb ft).

7. Install the catalytic converter. Refer to Catalytic Converter Replacement - Left Side.
8. Install the oil level indicator. Refer to Oil Level Indicator and Tube Replacement.
9. Install the exhaust manifold heat shield. Refer to Exhaust Manifold Heat Shield Replacement - Left Side.