Due to a Federally-mandated extended warranty covering emission-related components like the catalytic converter, it's advisable to consult a dealer service department before replacing the converter at your own expense. A catalytic converter, or catalyst, is an emission control device in the exhaust system that reduces certain pollutants in the exhaust gas stream, with two types available: an oxidation catalyst that reduces hydrocarbons and carbon monoxide, and a reduction catalyst that reduces oxides of nitrogen. Models equipped with three-way catalysts can reduce all three pollutants. Testing equipment for a catalytic converter is costly, so if a malfunction is suspected, it's best to take the vehicle to a dealer or authorized emission inspection facility for diagnosis and repair. When servicing underbody components, inspect the converter for leaks, corrosion, dents, and other damage, particularly at the welds and flange bolts. Although catalytic converters rarely break, they can become clogged; checking for a restricted converter can be done using a vacuum gauge to assess the effect of a blocked exhaust on intake vacuum. For replacement, on four-cylinder models, open the hood and remove the three upper exhaust pipe-to-exhaust manifold flange nuts, then raise the vehicle securely on jackstands and remove the three bolts attaching the exhaust pipe behind the catalytic converter to the resonator pipe flange before removing the catalytic converter itself. Discard old flange gaskets and ensure new gaskets are used during installation, along with new nuts and bolts, while coating threads with anti-seize compound. For V6 models, the front catalyst requires disconnecting the downstream
Oxygen Sensor, raising the vehicle, and removing the necessary flange nuts and bolts before removing the front catalyst/exhaust pipe assembly, again discarding old gaskets and using new ones during installation. The rear catalyst involves removing the heat shield, disconnecting the downstream oxygen sensor, and following a similar process to remove the rear catalyst/exhaust pipe assembly, ensuring new gaskets and fasteners are used during reinstallation.