GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Cobalt 🢒 Engine 🢒 Engine Cooling 🢒 Heated Oxygen Sensor Replacement - Sensor 1

Special Tools

J 39194 Oxygen Sensor Wrench

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.

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


    Object Number: 1825750 Size: SH
  1. Open the hood.
  2. Remove the underhood junction block bracket. Refer to Underhood Electrical Center or Junction Block Bracket Replacement.
  3. Remove the connector position assurance (CPA) retainer.
  4. Disconnect the engine wiring harness electrical connector (1) from the HO2S electrical connector (3).
  5. Remove the HO2S electrical connector clip (2) from the camshaft cover.

    6. Object Number: 1828436 Size: SH
  6. Using the J 39194 , remove the position 1 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: 1828436 Size: SH
  1. If reinstalling the old HO2S, coat the threads with anti-seize compound GM P/N 12377953 or equivalent.
  2. Using the J 39194 , install the position 1 HO2S.

    3. Tighten
    Tighten the sensor to 42 N·m (31 lb ft).


    Object Number: 1825750 Size: SH
  3. Connect the engine wiring harness electrical connector (1) to the HO2S electrical connector (3).
  4. Install the HO2S electrical connector clip (2) to the camshaft cover.
  5. Install the CPA retainer.
  6. Install the underhood junction block bracket. Refer to Underhood Electrical Center or Junction Block Bracket Replacement.
  7. Close the hood.