GM Service Manual Online
For 1990-2009 cars only

Removal Procedure

Notice: 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.

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

Notice: Refer to Heated Oxygen Sensor Resistance Learn Reset Notice in the Preface section.

Important: 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).

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


    Object Number: 1578458  Size: SH
  1. Remove the connector position assurance (CPA) retainer (3).
  2. Disconnect the HO2S electrical connector (2).

  3. Object Number: 1578459  Size: SH
  4. Remove the HO2S electrical connector clip from the thermostat housing.

  5. Object Number: 1523743  Size: SH
  6. Remove the HO2S.

Installation Procedure

Important: A special anti-seize compound is used on the HO2S 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 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 before installation.

    Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 1523743  Size: SH
  1. If reinstalling the old HO2S, coat the threads with anti-seize compound GM P/N 12377953 or equivalent.
  2. Install the HO2S.
  3. Tighten
    Tighten the HO2S to 41 N·m (30 lb ft).


    Object Number: 1578459  Size: SH
  4. Install the HO2S electrical connector clip to the thermostat housing.

  5. Object Number: 1578458  Size: SH
  6. Connect the HO2S electrical connector (2).
  7. Install the CPA retainer (3).