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Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSPONTIAC2008GRAND PRIX BASEREPAIR AND DIAGNOSISENGINE MECHANICALENGINE EXHAUST SYSTEMREPAIR INSTRUCTIONSCATALYTIC CONVERTER REPLACEMENT (LS4)INSTALLATION PROCEDURE

2008 Pontiac Grand Prix Base

Installation Procedure

2008 Pontiac Grand Prix BaseSECTION Installation Procedure

NOTE: 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.

Fig 1: Identifying HO2S

GM1553063

Courtesy of GENERAL MOTORS CORP.

Install the HO2S, if required.

Fig 2: Catalytic Converter Hangers

GM1553064

Courtesy of GENERAL MOTORS CORP.

Install NEW gaskets to the exhaust manifold and muffler studs.
Position the catalytic converter into place.
Install the catalytic converter hangers (1) to the converter.

Fig 3: Exhaust Manifold Pipe & Gasket

GM1553053

Courtesy of GENERAL MOTORS CORP.

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.