GM Service Manual Online
For 1990-2009 cars only

Removal Procedure

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.


    Object Number: 1618526  Size: SH
  1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
  2. Remove the connector position assurance (CPA) retainer (1).
  3. Disconnect the heated oxygen sensor (HO2S) electrical connector (3).
  4. Remove the HO2S electrical connector clip from the heat shield.

  5. Object Number: 1618528  Size: SH
  6. Remove the HO2S from the catalytic converter.

Installation Procedure

Important: A special anti-seize compound is use on the HO2S threads. The compound consists of liquid graphite and glass beads. The graphite tends to burns 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 be reinstalled, the threads must have anti-seize compound applied before reinstallation.


    Object Number: 1618528  Size: SH
  1. If re-installing the old sensor, coat the threads with the anti-seize compound P/N 12377953, or equivalent.
  2. Notice: Refer to Fastener Notice in the Preface section.

  3. Install the HO2S to the catalytic converter.
  4. Tighten
    Tighten the sensor to 42 N·m (31 lb ft).


    Object Number: 1618526  Size: SH
  5. Connect the HO2S electrical connector (3).
  6. Install the CPA retainer (1).
  7. Install the HO2S electrical connector clip to the heat shield.
  8. Lower the vehicle.