Installation Procedure

WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Refer to EXHAUST SYSTEM INSPECTION NOTICE in Cautions and Notices.

NOTE: Refer to FASTENER NOTICE in Cautions and Notices.

If necessary, install the oxygen sensors.
1. 1.1 Apply anti-seize compound GM P/N 12377953 or equivalent to the threads of the old oxygen sensors.
2. 1.2 Install the oxygen sensors.
Tighten

Tighten the sensors to 42 N.m (31 lb ft).
Install the catalytic convertor.

Fig 1: Installing Oxygen Sensors (4.3L, 4.8L & 5.3L)
Courtesy of GENERAL MOTORS CORP.
Install NEW exhaust manifold pipe seals to the exhaust manifolds.
Install the right exhaust manifold pipe nuts until sung.

Fig 2: Installing Right Exhaust Manifold Pipe Seals & Nuts (4.3L, 4.8L & 5.3L)
Courtesy of GENERAL MOTORS CORP.
Install the left exhaust manifold pipe nuts until snug.
Tighten the exhaust manifold pipe nuts.
Tighten

Tighten the nuts to 50 N.m (39 lb ft).

Fig 3: Installing Left Exhaust Manifold Pipe Nuts (4.3L, 4.8L & 5.3L)
Courtesy of GENERAL MOTORS CORP.
Install the exhaust muffler nuts.
Tighten

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

Fig 4: Installing Exhaust Muffler Nuts (4.3L, 4.8L & 5.3L)
Courtesy of GENERAL MOTORS CORP.
Connect the oxygen sensor electrical connectors (1, 2).
Connect the CPA retainers.
Clip the oxygen sensors electrical connectors to the following:
- Hose clip
- Transmission crossmember
Fig 5: Connecting Oxygen Sensor Electrical Connectors At Hose Clip & Transmission Crossmember (4.3L, 4.8L & 5.3L)
Courtesy of GENERAL MOTORS CORP.
Connect the oxygen sensor electrical connectors.
Connect the CPA retainers.
Install the clip around the engine harness and the oxygen sensor pigtail.

Fig 6: Connecting Oxygen Sensor Electrical Connectors, CPA Retainers & Clip (4.3L, 4.8L & 5.3L)
Courtesy of GENERAL MOTORS CORP.
Connect the oxygen sensor electrical connector.
If equipped, clip the oxygen sensor connection to the floor reinforcement.
Lower the vehicle.

Fig 7: Connecting Oxygen Sensor Electrical Connectors & Clip At Floor Reinforcement (4.3L, 4.8L & 5.3L)
Courtesy of GENERAL MOTORS CORP.