For 1990-2009 cars

#### Special Tools

J 39194-C Oxygen Sensor Wrench

### Removal Procedure

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.

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

Note:

• | 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 heated oxygen sensor (HO2S).

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

1. Remove the exhaust manifold heat shield studs (2).
2. Remove the exhaust manifold heat shield (1).
3. If equipped with regular production option (RPO) MN5, perform the following steps, remove the connector position assurance (CPA) retainer.
4. Disconnect the engine harness electrical connector (2) from the HO2S.
5. Remove the HO2S connector clip from the thermostat housing.
6. If equipped with RPO M86, perform the following steps, remove the CPA retainer (2).
7. Disconnect the engine harness electrical connector (1) from the HO2S.
8. Remove the HO2S connector clip from the thermostat housing.
9. Using the J 39194-C , remove the HO2S.

### Installation Procedure

Note: A special anti-seize compound is used on the heated oxygen sensor threads. The compound consists of a liquid graphite and glass beads. The graphite will burn away, but the glass beads will remain, making the sensor easier to remove. New or service replacement sensors will have the compound applied to the threads. If a sensor is removed and is to be reinstalled, the threads must have an anti-seize compound applied prior to installation.

1. If necessary, coat the threads of the HO2S with anti-seize compound GM P/N 12377953 or Saturn P/N 21485279 or equivalent.

Caution: Refer to Component Fastener Tightening Caution in the Preface section.

2. Using the J 39194-C , install the HO2S to 42 N·m (31 lb ft).
3. If equipped with RPO M86, perform the following steps, connect the engine harness electrical connector (1) to the HO2S.
4. Install the CPA retainer (2).
5. Install the HO2S connector clip to the thermostat housing.
6. If equipped with RPO MN5, perform the following steps, connect the engine harness electrical connector (2) to the HO2S.
7. Install the CPA retainer.
8. Install the HO2S connector clip to the thermostat housing.
9. Install the exhaust manifold heat shield (1).
10. Install the exhaust manifold heat shield studs (2) and tighten to 22 N·m (16 lb ft).