Installation Procedure

WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

Install the catalytic converter (1) in reverse order of removal by starting with the outlet pipe angled toward the left side of the vehicle.

Fig 1: Installing Catalytic Converter
Courtesy of GENERAL MOTORS CORP.
Install the exhaust muffler nuts. Position the catalytic converter in the installed location before tightening the nuts.
Tighten

Tighten the nuts to 45 N.m (33 lb ft).

Fig 2: Installing Exhaust Muffler Nuts
Courtesy of GENERAL MOTORS CORP.
Install the right exhaust manifold pipe nuts. Position the catalytic converter in the installed location before tightening the nuts.
Tighten

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

Fig 3: Installing Right Exhaust Manifold Pipe Nuts
Courtesy of GENERAL MOTORS CORP.
Install the left exhaust manifold pipe nuts.
Tighten

Tighten the nuts to 50 N.m (37 lb ft).
If equipped with 4WD, install the front propeller shaft to the drive axle. Refer to PROPELLER SHAFT REPLACEMENT - FRONT in Propeller Shaft.
Install the rear propeller shaft. Refer to PROPELLER SHAFT AND UNIVERSAL JOINTS in Propeller Shaft.
Lower the transmission.
Install the transmission support.

Fig 4: Installing Left Exhaust Manifold Pipe Nuts
Courtesy of GENERAL MOTORS CORP.

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 an exhaust component and if for any reason the sensor is to be reinstalled, the threads must have anti-seize compound applied before the reinstallation.
If reinstalling the old sensors, coat the threads with anti-seize compound GM P/N 12377953, or equivalent.
NOTE: Refer to COMPONENT FASTENER TIGHTENING NOTICE in Cautions and Notices.

IMPORTANT: If the HO2S sensor is connected to the main wiring harness during installation. Rotate the HO2S sensor several turns counterclockwise before threading the HO2S sensor into the catalytic converter. This action of initially reverse winding of the pigtail wires will prevent a condition where the HO2S sensor pigtail wires become severely twisted or binding once the HO2S sensor is installed into the catalytic converter.
Install both front HO2S sensors (1) to the catalytic converter.
Tighten

Tighten the sensor to 42 N.m (31 lb ft).
Install both rear HO2S (2) to the catalytic converter.
Tighten

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

Fig 5: Installing Front & Rear HO2S Sensors To Catalytic Converter
Courtesy of GENERAL MOTORS CORP.