GM 25904628 Converter Assembly

A catalytic converter is an emission control device that reduces certain pollutants. There are two types of converters: an oxidation catalyst that reduces hydrocarbons and carbon monoxide, and a reduction catalyst that reduces oxides of nitrogen. Vehicles are equipped with two three-way catalysts that can reduce all three pollutants. Whenever you raise the vehicle to service underbody components, inspect the converter for leaks, corrosion, dents, and other damage. The easiest way to check for a restricted converter is to use a vacuum gauge to diagnose the effect of a blocked exhaust on the intake vacuum. To remove the converter, raise the vehicle and place it securely on jack stands, disconnect the electrical connectors for the upstream and downstream oxygen sensors, remove all four sensors, remove the nuts at each of the upper flanges that secure the front exhaust pipe assembly to the exhaust manifold flanges, remove the nuts that secure the rear flange of the front exhaust pipe assembly to the rest of the exhaust system, and remove the front exhaust pipe assembly. To install the converter, coat the threads of the nuts and bolts with an anti-seize compound to facilitate future removal and tighten the nuts that secure the front exhaust pipe assembly to the exhaust manifold and to the rest of the exhaust system securely.