GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1998 🢒 Regal 🢒 Engine 🢒 Engine Exhaust 🢒 Exhaust System Replacement

Removal Procedure
  1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Disconnect the heated oxygen sensor (HO2S) wiring harness connector and retainers. Refer to Heated Oxygen Sensor Replacement or Heated Oxygen Sensor Replacement in Engine Controls - 3.1L or Heated Oxygen Sensor Replacement in Engine Controls - 3.8L.

    3. Notice: To prevent internal damage to the flexible coupling of the catalytic converter assembly, the converter must be supported. The vertical movement at the rear of the catalytic converter assembly must not exceed 6 degrees up or down.

  3. Suitably support the exhaust system.
  4. Disconnect the exhaust system hangers from the exhaust system.

    5. Object Number: 372616 Size: SH
  5. Remove the catalytic converter bolts from the three-way catalytic converter pipe flange.

    6. Object Number: 289492 Size: SH
  6. Remove the exhaust system.

    7. Object Number: 372621 Size: SH
  7. Remove the exhaust manifold pipe stud nuts from the exhaust manifold pipe studs.
  8. Remove the three-way catalytic converter.
  9. Remove the exhaust manifold pipe gasket.

    10. Object Number: 372612 Size: SH
  10. Remove the heated oxygen sensor (HO2S). Refer to Heated Oxygen Sensor Replacement or Heated Oxygen Sensor Replacement in Engine Controls - 3.1L or Heated Oxygen Sensor Replacement in Engine Controls - 3.8L.

Installation Procedure

    Object Number: 372612 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. Install the heated oxygen sensor (HO2S). Refer to Heated Oxygen Sensor Replacement or Heated Oxygen Sensor Replacement in Engine Controls - 3.1L or Heated Oxygen Sensor Replacement in Engine Controls - 3.8L.

    2. Object Number: 372621 Size: SH
  2. Install the exhaust manifold pipe gasket.
  3. Install the three-way catalytic converter.
  4. Install the exhaust manifold pipe stud nuts to the exhaust manifold pipe studs.

    5. Tighten
    Tighten the exhaust manifold pipe stud nuts to 32 N·m (24 lb ft).


    Object Number: 289492 Size: SH

    Notice: To prevent internal damage to the flexible coupling of the catalytic converter assembly, the converter must be supported. The vertical movement at the rear of the catalytic converter assembly must not exceed 6 degrees up or down.

  5. Install the exhaust system.
  6. Connect the exhaust system hangers to the exhaust system.

    7. Object Number: 372616 Size: SH
  7. Install the catalytic converter bolts through the three-way catalytic converter pipe flange.

    8. Tighten
    Tighten the catalytic converter bolts to 45 N·m (33 lb ft).

  8. Remove the support from the exhaust system.
  9. Connect the heated oxygen sensor (HO2S) wiring harness connector and retainers. Refer to Heated Oxygen Sensor Replacement or Heated Oxygen Sensor Replacement in Engine Controls - 3.1L or Heated Oxygen Sensor Replacement in Engine Controls - 3.8L.
  10. Lower the vehicle.
  11. Inspect the exhaust system for leaks and underbody contact.