GM Service Manual Online
For 1990-2009 cars only

Removal Procedure


    Object Number: 12348  Size: SH

    Notice: Do not remove the pigtail from either the heated oxygen sensor (HO2S) or the oxygen sensor (O2S). Removing the pigtail or the connector will affect sensor operation.

    Handle the oxygen sensor carefully. Do not drop the HO2S. Keep the in-line electrical connector and the louvered end free of grease, dirt, or other contaminants. Do not use cleaning solvents of any type.

    Do not repair the wiring, connector or terminals. Replace the oxygen sensor if the pigtail wiring, connector, or terminal is damaged.

    This external clean air reference is obtained by way of the oxygen sensor signal and heater wires. Any attempt to repair the wires, connectors, or terminals could result in the obstruction of the air reference and degraded sensor performance.

    The following guidelines should be used when servicing the heated oxygen sensor:

       • Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance.
       • Do not damage the sensor pigtail and harness wires in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems.
       • Ensure the sensor or vehicle lead wires are not bent sharply or kinked. Sharp bends or kinks could block the reference air path through the lead wire.
       • Do not remove or defeat the oxygen sensor ground wire, where applicable. Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will cause poor engine performance.
       • Ensure that the peripheral seal remains intact on the vehicle harness connector in order to prevent damage due to water intrusion. The engine harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed.

    Important: Use care when you handle the HO2S. Keep the in-line electrical connector and the louvered end free of grease, dirt, or other contaminants. Do not use any cleaning solvents. Do not drop or roughly handle the heated oxygen sensor or catalyst monitor. If you drop the sensor, replace the sensor.

    Important: The heated oxygen sensor may be difficult to remove when the engine temperature is below 48°C (120°F). Excess force may damage the threads in the exhaust manifold or the exhaust pipe.

  1. If you replace the H02S , remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement in Engine Mechanical.
  2. If you replace the HO2S 2, raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.

  3. Object Number: 32187  Size: SH
  4. Disconnect the electrical connector.
  5. Carefully back out the heated oxygen sensor.

Installation Procedure


    Object Number: 32187  Size: SH

    Important: A special anti-seize compound is used on the Heated Oxygen Sensor threads. The compound consists of graphite suspended in fluid 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 you remove a sensor from an engine and you re-install the sensor, apply an anti-seize compound to the threads before reinstallation.

  1. Coat the threads of the HO2S or the catalyst monitor with anti-seize compound P/N 5613695, or equivalent, if necessary.

  2. Object Number: 12348  Size: SH
  3. Install the heated oxygen sensor.
  4. Tighten
    Tighten the heated oxygen sensor to 41 N·m (30 lb ft).

  5. Connect the electrical connector.
  6. If you replace the H02S 1, install the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement in Engine Mechanical.
  7. If you replace the HO2S 2, lower the vehicle.