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HOMESERVICE MANUALSCHEVROLET2006CHEVY EXPRESS G2500, VAN CARGO, 6.6 2REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1623 (ENGINE EXHAUST SYSTEM)REPAIR INSTRUCTIONSCATALYTIC CONVERTER REPLACEMENT (WITH V8 ENGINE)REMOVAL PROCEDURE
2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2

Removal Procedure

2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2SECTION Removal Procedure
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
    Fig 1: View Of Oil Pan Skid Plate & Bolts
    GM1698082Courtesy of GENERAL MOTORS CORP.
  1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
  2. Remove the oil pan skid plate bolts and skid plate, if equipped.
  3. Remove the transmission crossmember. Refer to Transmission Support Crossmember Replacement (2WD 1500/2500) , Transmission Support Crossmember Replacement (4WD 1500/2500) , Transmission Support Crossmember Replacement (2WD 2500 HD/3500) or Transmission Support Crossmember Replacement (4WD 2500 HD/3500) .
    4. Fig 2: View Of Engine Wiring Harness Electrical Connectors, (CPA) Retainers & Engine Harness Clips
    GM1704006Courtesy of GENERAL MOTORS CORP.
  4. Remove the right front connector position assurance (CPA) retainer (2).
  5. Disconnect the right front heated oxygen sensor (HO2S) electrical connector from the engine wiring harness electrical connector (1).
  6. Remove the right rear CPA retainer (4).
  7. Disconnect the engine wiring harness electrical connector (3) from the right rear HO2S electrical connector.
  8. Remove the right rear HO2S electrical connector clip from the engine harness clip (5).
    9. Fig 3: View Of Left Rear CPA Retainer & Engine Wiring Harness Electrical Connector
    GM1704005Courtesy of GENERAL MOTORS CORP.
  9. Remove the left rear CPA retainer (1).
  10. Disconnect the left rear HO2S electrical connector from the engine wiring harness electrical connector (3).
    11. Fig 4: View Of Left Front HO2S Electrical Connector Clip & Engine Wiring Harness Electrical Connector
    GM1704004Courtesy of GENERAL MOTORS CORP.
  11. For vehicles equipped with 2ML70 (2-Mode), unbolt harness retainer bracket. Unclip and reposition harness.

    For vehicles equipped with a 4L60-E/4L70-E automatic transmission perform the following steps, for vehicles equipped with a 6L80-E automatic transmission proceed to step 15.

  12. Remove the left front CPA retainer.
  13. Disconnect the engine wiring harness electrical connector (2) from the left front HO2S.
  14. Remove the left front HO2S electrical connector clip (1) from the fuel line clip.
    15. Fig 5: View Of Engine Wiring Harness Electrical Connector Clip & Electrical Connector
    GM1704002Courtesy of GENERAL MOTORS CORP.
  15. Remove the left front CPA retainer (2).
  16. Remove the engine wiring harness electrical connector clip (1) from the fuel line clip.
  17. Disconnect the engine wiring harness electrical connector (3) from the left front HO2S.
    18. Fig 6: View Of Catalytic Converter To Muffler Nuts
    GM1708705Courtesy of GENERAL MOTORS CORP.
  18. If the vehicle is a 1500 series, remove the catalytic converter to muffler nuts.
  19. If the vehicle is 2-Mode, loosen the clamp and disconnect the exhaust from the catalytic converter.
    20. Fig 7: View Of Catalytic Converter To Muffler Nuts (RPO L92)
    GM1708979Courtesy of GENERAL MOTORS CORP.
  20. If the vehicle is a 2500/3500 series, remove the muffler to catalytic converter nuts.
  21. Remove the HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series - Cab/Chassis) , Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series) or Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (1500 Series) .
    22. Fig 8: View Of Catalytic Converter To Exhaust Manifold Nuts & Exhaust Seals
    GM1708626Courtesy of GENERAL MOTORS CORP.
  22. Remove the catalytic converter to exhaust manifold nuts (1). (1500 series shown, 2500/3500 series similar).
  23. Separate the catalytic converter assembly from the exhaust manifolds.
  24. Remove the catalytic converter assembly from the exhaust muffler.
  25. If replacing the catalytic converter assembly, perform the following steps, otherwise proceed to step 4 in the installation procedure.
  26. Remove the exhaust seals (2 and 3).
    27. Fig 9: View Of Catalytic Converter Assembly HO2S's
    GM1704008Courtesy of GENERAL MOTORS CORP.
  27. Remove the HO2S (1-5) from the catalytic converter assembly. (1500 series shown, 2500/3500 series similar).
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.