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

Removal Procedure
  1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.
  2. Remove the transmission crossmember. Refer to Crossmember Replacement.

    3. Object Number: 1704008 Size: SH
  3. If replacing the three way catalytic converter remove the heated oxygen (HO2S) sensors (1 - 5) otherwise disconnect the heated oxygen (HO2S) sensors harness connectors. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 , Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 , Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 and Heated Oxygen Sensor Replacement - Bank 2 Sensor 2.

    4. Object Number: 1708626 Size: SH
  4. Remove the catalytic converter pipe to the exhaust manifold nuts (1).
  5. Remove the exhaust seals (2 and 3) and discard.

    6. Object Number: 1936687 Size: SH
  6. Loosen the band clamp bolt (1).
  7. Remove the catalytic converter pipe from the vehicle.

Installation Procedure

    Object Number: 1708626 Size: SH
  1. Install NEW exhaust manifold seals (2 and 3).
  2. Install the catalytic converter pipe to the exhaust manifolds.

    3. Caution: Refer to Fastener Caution in the Preface section.

  3. Install the catalytic converter pipe to exhaust manifold nuts (1) and tighten to 50 N·m (37 lb ft).

    4. Object Number: 1936687 Size: SH
  4. Position the three way converter to the muffler assembly and tighten the clamp bolt (1) to 44 N·m(32 lb ft).
  5. Install the transmission crossmember. Refer to Crossmember Replacement.

    6. 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.


    Object Number: 1704008 Size: SH
  6. If replacing the three way catalytic converter Install the heated oxygen (HO2S) sensors (1 - 5) otherwise Connect the heated oxygen (HO2S) sensors harness connectors. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 , Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 , Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 and Heated Oxygen Sensor Replacement - Bank 2 Sensor 2.
  7. Lower the vehicle.
  8. Inspect for exhaust leaks.