MIL Light On, DTC P0141 Set (Repalce Oxygen Sensor, HO2S 2)

Some owners may comment on an illumination of the Malfunction Indicator Lamp (MIL). Upon investigation, the technician will find a Diagnostic Trouble Code P0141 (heater circuit malfunction).

This Diagnostic Trouble Code may be due to the oxygen sensor that monitors the efficiency of the catalytic converter (post catalytic converter location).

Replace the oxygen sensor (HO2S 2) using the following procedure:

REAR HEATED OXYGEN SENSOR (HO2S 2)

Important: The HO2S 2 uses a permanently attached pigtail and connector. This pigtail should not be removed from the HO2S 2. Damage or removal of the pigtail or connector could affect proper operation of the HO2S 2.

Important: Take care when handling the HO2S 2. The in-line electrical connector and louvered end must be kept free of grease, dirt or other contaminants. Avoid using cleaning solvents of any type. DO NOT drop or roughly handle the HO2S 2.

Removal

1. Turn OFF the ignition.
2. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information of the applicable Service Manual.

Caution:  Exhaust system may be extremely hot. Avoid contact with hot surfaces in order to prevent physical injury.

3. Disconnect the HO2S 2 electrical connector.

Notice: Excessive force may damage the threads in the exhaust system.

4. Remove the HO2S 2.

Important: A special anti-seize compound is used on the HO2S 2 sensor threads. The compound consists of 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 sensors will already have the compound applied to the threads. If the sensor is removed from the exhaust, and if for any reason it is to be reinstalled, the threads must have an anti-seize compound applied before reinstallation.

Installation

1. Coat the threads of the HO2S 2 with anti-seize compound, P/N 12377953 (in Canada, use P/N 993032), if necessary.
2. Install the HO2S 2

Tighten
Tighten the HO2S 2 to 41 N·m (30 lb ft).

3. Connect the HO2S 2 electrical connector.
4. Lower the vehicle

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: