Because of a Federally mandated extended warranty covering emissions-related components like the catalytic converter, it is advisable to consult a dealer service department before replacing the converter at your own expense. The catalytic converter is an emission control device added to the exhaust system to reduce pollutants from the exhaust gas stream, with two types available: the conventional oxidation catalyst, which reduces hydrocarbon and carbon monoxide levels, and the three-way catalyst, which lowers oxides of nitrogen, hydrocarbons, and carbon monoxide. Models from 2001 to 2006 feature three catalytic converters, including a warm-up three-way catalytic converter as part of the front exhaust manifold and another in the pipe from the rear manifold, with the main exhaust pipe containing the final converter. The test equipment for diagnosing a malfunctioning converter is expensive and sophisticated, so it is recommended to take the vehicle to a dealer or authorized emissions inspection facility for diagnosis and repair. When servicing underbody components, check the converter for leaks, corrosion, dents, and other damage, and inspect the welds and flange bolts attaching the converter to the exhaust system; if any damage is found, replacement is necessary. Although catalytic converters rarely break, they can become plugged, and a vacuum gauge can be used to check for a restricted converter by connecting it to an intake manifold vacuum source, warming the engine, and recording vacuum readings at idle and after quickly opening the throttle. If the reading after the fourth test is more than one in-Hg lower than the idle reading, the exhaust system may be restricted. For models from 2001 and later, warm-up converters cannot be replaced separately, so it is important to spray the nuts on the exhaust flange studs with penetrating oil before removal, disconnect the flange at the rear of the converter, and cut the front of the converter from the pipe for removal, with installation being the reverse of removal.
Posted by ToyotaPartsDeal Specialist 
