A: The catalytic converter is an emission control device that reduces pollutants in the exhaust gas stream. It consists of an oxidation catalyst and a reduction catalyst. The PCM monitors the oxygen content using Oxygen Sensors. Testing requires expensive equipment, so it is recommended to take the vehicle to a dealer or authorized emissions inspection facility. Regular inspections should be done to check for leaks, corrosion, and other damage. A vacuum gauge can be used to check for a restricted converter. To replace the catalytic converter, the vehicle should be raised and securely placed on jackstands. The downstream oxygen sensor should be removed, and the nuts and bolts should be loosened. When purchasing a new unit, it is important to ensure that it is identical to the old one. Before installation, the threads of the nuts and bolts should be coated with anti-seize compound.