For 1990-2009 cars

### Removal Procedure

Caution: Refer to Heated Oxygen and Oxygen Sensor Caution in the Preface section.

1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle.
2. Remove the connector position assurance (CPA) retainer (3).
3. Disconnect the heated oxygen sensor (HO2S) electrical connector (4) from the engine wiring harness electrical connector (1).
4. Remove the HO2S (4) from the exhaust pipe.

### 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 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 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 (4) to the exhaust pipe.

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

3. Connect the HO2S electrical connector (4) to the engine wiring harness electrical connector (1).
4. Install the CPA retainer (3).
5. Lower the vehicle.