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Installation Procedure

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IMPORTANT: A special anti-seize compound is used on the HO2S threads. The compound consists of liquid graphite and glass beads. The graphite tends to burn 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 as exhaust component and if for any reason the sensor is to be reinstalled, the threads must have anti-seize compound applied before the reinstallation.
    Fig 1: View Of Catalytic Converter Assembly HO2S's
    GM1704012Courtesy of GENERAL MOTORS CORP.
  1. If replacing the catalytic converter assembly, perform the following steps, otherwise proceed to step 4.
  2. If reinstalling the old sensors, coat the threads with anti-seize compound GM P/N 12377953, or equivalent.
    3. NOTE: Replacement components must be the correct part number for the application. Components requiring the use of the thread locking compound, lubricants, corrosion inhibitors, or sealants are identified in the service procedure. Some replacement components may come with these coatings already applied. Do not use these coatings on components unless specified. These coatings can affect the final torque, which may affect the operation of the component. Use the correct torque specification when installing components in order to avoid damage.
    NOTE: Refer to Fastener Notice .
  3. Install the HO2S's (1 and 4) to the catalytic converter assembly.

    Tighten:  Tighten the sensors to 42 N.m (31 lb ft).

    4. Fig 2: View Of Catalytic Converter Hanger, Exhaust Manifold Nuts & Exhaust Seal
    GM1708730Courtesy of GENERAL MOTORS CORP.
  4. Install the NEW exhaust seal (3) as required.
  5. Slide the catalytic converter hanger (1) into the hanger bracket.
  6. Install the catalytic converter to the exhaust manifold studs.
  7. Install the catalytic converter to exhaust manifold nuts (2).

    Tighten:  Tighten the nuts to 50 N.m (37 lb ft).

    8. Fig 3: View Of Left Rear CPA Retainer & Engine Wiring Harness Electrical Connector
    GM1704005Courtesy of GENERAL MOTORS CORP.
  8. Connect the left rear HO2S electrical connector to the engine wiring harness electrical connector (3).
  9. Install the left rear CPA retainer (1).
    10. Fig 4: View Of Left Front CPA Retainer & Engine Wiring Harness Electrical Connector
    GM1704010Courtesy of GENERAL MOTORS CORP.
  10. Connect the left front HO2S electrical connector (2) to the engine wiring harness electrical connector (3).
  11. Install the left front CPA retainer (2).
    12. Fig 5: View Of Oil Pan Skid Plate & Bolts
    GM1698083Courtesy of GENERAL MOTORS CORP.
  12. Install the muffler. Refer to Muffler Replacement (1500 - w/RPO L92)  or Muffler Replacement (1500 - w/RPOs LC9/LMG/LY5/L76)  or Muffler Replacement (1500 - w/RPOs LMG/LY2/LY5)  or Muffler Replacement (2500) .
  13. Position the oil pan skid plate and tighten until snug the 2 rear oil pan skid plate bolts, install the 2 front oil pan skid plate bolts, if equipped.

    Tighten:  Tighten the bolts to 28 N.m (21 lb ft).

  14. Lower the vehicle.
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