The catalytic converter is an emission control device in the exhaust system that reduces pollutants from exhaust gases, with two types, the oxidation catalyst, which reduces hydrocarbon and CO by oxidation and convert them into water vapor and carbon dioxide and the reduction catalyst, which reduces the oxides of nitrogen by non-oxidation and gives Nitrogen and Oxygen. These catalysts are integrated in a single three way catalyst which deals with all the three pollutants. The functioning of the catalyst depends on the degree of its oxygen supply; its efficiency is achieved at the fuel/air equivalence ratio of 14.7. If the air/fuel mixture is very weak it will be possible to store more and more of excess oxygen in the catalyst chamber, while, if the mixture is poor or rich in fuel it is possible to 'use' all the oxygen in the catalyst and so make it ineffective. The storage capacity of the catalyst decreases over time, as is detected by the PCM through the upstream and downstream 
Oxygen Sensors; the sensors send a Diagnostic Trouble Code when the catalyst is failing and the Malfunction Indicator Light is on. All of the models equipped with two catalytic converters that have inlet pipes welding to each catalyst, while different connecting to the outlet pipes corresponding to the engine type. Given the complexity of the converter, it is advisable to seek professional help when the component is being tested for it, usually, entails the use of specific tools. As, for example, when working on the underbody parts, it is important to carry out monthly inspections of leaks, corrosion and damages. Although failures are rare, plugged converters can be diagnosed with reference to a vacuum gauge to check the exhaust impediments. Replacement procedures include making sure that the exhaust system is cool, disconnecting the oxygen sensor, removing the entire catalyst assembly, and then checking for signs of corrosion on the fasteners before the procedures of installation are done in the reverse order of removal of the fasteners and then checking for tightness.