Pollutants in exhaust gas can be lessened by a catalytic converter. Oxidation converters and reduction converters are the two main types of converters. There is need for specialized equipment to check for problems and this should be done by a professional. A vacuum gauge can be used to test for a clogged converter. To change on certain models of Acura and Honda, lift up the vehicle, unplug the 
Oxygen Sensor, take off retaining nuts, and replace corroded fasteners.