GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 HUMMER 🢒 2007 🢒 H2 🢒 Engine 🢒 Engine Exhaust 🢒 Catalytic Converter Replacement

Removal Procedure
  1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
  2. Remove the catalytic converter guard, if equipped. Refer to Catalytic Converter Guard Replacement.

    3. Object Number: 664828 Size: SH
  3. Disconnect the oxygen sensor electrical connectors.
  4. Remove the oxygen sensor pigtails from the frame rail.

    5. Object Number: 664951 Size: SH
  5. Unclip the oxygen sensor pigtails from the crossmember and the transmission.
  6. Disconnect the oxygen sensor electrical connectors (1, 2).

    7. Object Number: 858550 Size: SH
  7. Remove the left exhaust manifold to catalytic converter nuts.

    8. Object Number: 858553 Size: SH
  8. Remove the right exhaust manifold to catalytic converter nuts.

    9. Object Number: 664840 Size: SH
  9. Remove the muffler nuts.
  10. Remove the catalytic converter from the vehicle.

    11. Object Number: 664954 Size: SH
  11. Remove the oxygen sensors if the catalytic converter is to be replaced.

Installation Procedure

    Object Number: 664954 Size: SH

    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.

  1. If the catalytic converter was replaced, perform the following:
    2. 1.1. Apply anti-seize compound GM P/N 12377953 or equivalent to the threads of the old oxygen sensors.
    1.2. Install the oxygen sensors.

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

  2. Position the catalytic converter to the exhaust manifolds and the muffler pipe.

    3. Object Number: 858553 Size: SH
  3. Install NEW manifold seals to the manifolds.
  4. Install the right manifold to catalytic converter nuts until snug.

    5. Object Number: 858550 Size: SH
  5. Install the left manifold to catalytic converter nuts until snug.
  6. Tighten the left and the right manifold to catalytic converter nuts.

    7. Tighten
    Tighten the catalytic converter nuts to 50 N·m (39 lb ft).


    Object Number: 664840 Size: SH
  7. Install the muffler nuts to the catalytic converters .

    8. Tighten
    Tighten the muffler nuts to 40 N·m (30 lb ft).


    Object Number: 664951 Size: SH
  8. Connect the oxygen sensor electrical connectors (1, 2).
  9. Clip the oxygen sensors electrical pigtails to the crossmember and the transmission.

    10. Object Number: 664828 Size: SH
  10. Connect the oxygen sensor pigtails to the frame rail.
  11. Install the clip around the frame harness and the oxygen sensor pigtail.
  12. Lower the vehicle and inspect for exhaust leaks.