Q: What should you consider before replacing a catalytic converter on Saturn Vue?
A: Because of a Federally mandated extended warranty covering emissions-related components like the catalytic converter, it is advisable to check with a dealer service department before replacing the converter at your own expense. A catalytic converter is an emission control device in the exhaust system that reduces certain pollutants in the exhaust gas stream, with two types: oxidation converters and reduction converters. Oxidation converters contain a ceramic honeycomb substrate coated with platinum and palladium, reducing unburned hydrocarbons and carbon monoxide by adding oxygen to the exhaust stream, converting them to water vapor and carbon dioxide. Reduction converters, coated with platinum and rhodium, reduce oxides of nitrogen by removing oxygen, producing nitrogen and carbon dioxide. Catalytic converters that combine both types are known as three-way catalysts, capable of reducing all three pollutants. The test equipment for diagnosing a malfunctioning catalytic converter is expensive, so it is recommended to take the vehicle to a dealer or authorized emission inspection facility. 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 restricted; checking for a restricted converter can be done using a vacuum gauge connected to an intake manifold vacuum source. After warming the engine and noting the vacuum reading at idle, quickly open and close the throttle, recording the readings. If the fourth reading is more than one in-Hg lower than the idle reading, the exhaust system might be restricted. Many exhaust specialist shops can replace catalytic converters at a lower cost than a dealer. To replace a catalytic converter, raise the vehicle securely on jackstands, disconnect the electrical connector from the oxygen sensor, support the exhaust system as necessary, remove the retaining nuts from the catalyst mounting flanges, take off the catalyst and gaskets, and then install the new catalyst in reverse order, ensuring to replace any rusted or damaged fasteners and gaskets.