The catalytic converter is an emission control device in the exhaust system that reduces pollutants from exhaust gases, with two types, The oxidation catalyst reduces the hydrocarbon and carbon monoxide pollutant by combining with oxygen to form water vapor and carbon dioxide whereas the reduction catalyst reduces the oxide of nitogen pollutant by stripping off the oxygen to give nitrogen and oxygen. These catalysts are frequently integrated to form a so-called three-way catalyst covering all the codes. The working of the catalyst is based on the volume of oxygen that is fed to it; a perfect combination of air and fuel is 14.7,1. If the air/fuel ratio is too lean the catalyst can charge itself with oxygen or too rich a mixture and the oxygen holding capacity is used up. Oxygen can be stored on the catalyst and this depletes with time, the PCM later measures it with upstream and downstream
Oxygen Sensors. When the content of oxygen in the exhaust gases tend to be more than a specific level, a Diagnostic Trouble Code is registered and the Malfunction Indicator Light Lamp comes on. To perform the renowned check on a faulty catalytic converter usually needs some sophisticated tools, hence people are advised to consult an expert technician. Routine check-up for the presence of the leaks, corrosion, and damages is advised each time the car is being worked on. Despite these, instances of failure are exceptional, but plugged converters can be realized, while a vacuum gauge will indicate restrictions in the exhaust system. To remove a suspect converter, install a vacuum gauge with an intake manifold vacuum source, bring the engine to temp, and note vacuum at idle then with the throttle cracked. If the reading drops greatly in the subsequent tests, then probably the possibility of restriction is there. For replacement, safely lift the car, then loosen and unscrew the oxygen sensors, so that they can be replaced without being damaged. Undo the nut on the clamp holding the crossover pipe to allow the catalyst assemblies to be split then remove the nut holding the upper mounting flange to the exhaust manifold. Last of all, unbolt the catalyst assembly from the exhaust manifold, crossover pipe, and entire exhaust system and the rest are the installation procedures performed in sequence of the removal.