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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Monte Carlo 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Heated Oxygen Sensor Replacement

Heated Oxygen Sensor Replacement HO2S1

Removal Procedure

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


    Object Number: 12669 Size: SH
  1. Disconnect the electrical connector.

    2. 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 a sensor is removed from an engine and if for any reason is to be reinstalled, the threads must have anti-seize compound applied before reinstallation.

  2. Carefully back out the heated oxygen sensor.

Installation Procedure

    Object Number: 12669 Size: SH
  1. Coat the threads of heated oxygen sensor/catalyst monitor with anti-seize compound P/N 5613695, or equivalent if necessary.

    2. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  2. Install the Heated Oxygen Sensor.

    3. Tighten

        •  Tighten the H02S 1 (Pre-catalytic converter) to 42 ±4 N·m (31 lb ft).
        •  Tighten the H02S 2 (Post-catalytic converter) to 42 ±4 N·m (31 lb ft).
  3. Connect the electrical connector.

Heated Oxygen Sensor Replacement HO2S2

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.

Removal Procedure

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


    Object Number: 10975 Size: SH
  1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in general information.
  2. Disconnect the sensor electrical connector.

    3. 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 a sensor is removed from an engine and if for any reason is to be reinstalled, the threads must have anti-seize compound applied before reinstallation.

  3. Carefully back out the heated oxygen sensor.

Installation Procedure

    Object Number: 10975 Size: SH
  1. Coat the threads of heated oxygen sensor/catalyst monitor with anti-seize compound P/N 5613695, or equivalent if necessary.

    2. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  2. Install the Heated Oxygen Sensor.

    3. Tighten

        •  Tighten the H02S 1 (Pre-catalytic converter) to 42 ±4 N·m (31 lb ft).
        •  Tighten the H02S 2 (Post-catalytic converter) to 42 ±4 N·m (31 lb ft).

    Refer to

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

    in General Information.

  3. Connect the sensor electrical connector.
  4. Lower the vehicle.