Due to a Federally mandated warranty for emissions-related parts like the catalytic converter, the charger ought to consult the dealer's service department before getting the converter replaced on personal expense. The catalytic converter is an emission control device in the exhaust system that reduces pollutants from exhaust gases, with two types: the oxidation catalysts which increases the amount of oxygen for burning of hydrocarbons and carbon monoxide and the reduction catalysts which reduces the amount of oxides of nitrogen by stripping it off oxygen. These catalysts are combine into a system referred to as a three-way catalyst to combat all the three pollutants. The catalyst in question works based on the ingress of oxygen in the amounts necessary to effect a change in toxic pollutants. It works best at the air/fuel mix of 14.7:1 and should not be leaner or richer to avoid scarcity or abundance of oxygen. The powertrain control module gets information of the oxygen content through the upstream and downstream sensors and if the catalyst is not working it will send a Diagnostic Trouble Code and turn on the CHECK ENGINE light. If the car has a possible problem of a malfunctioning converter then it is advisable to consult a professional as diagnosis and repair involves expensive equipments. It is also necessary to check for signs of water leaks, signs of corrosion and signs of damage to the car in general and to the underbody components in particular. Even though catalytic converters are rather rugged, they can get restricted; a vacuum gauge will assist in finding this out by ensuring intake vacuum before and after throttling. For replacement, it is different depending on the engine, for 2.4L and 3.5L V6 the converters are underneath the exhaust manifolds while 2.7L and 3.3L V6 has the converter built-in to the exhaust manifold. The downstream catalytic converter is mounted on the front exhaust pipe just before the muffler, which is replaced at muffler shops with welding facilities, or by changing the entire exhaust pipe with a new one that has the catalytic converter. The other procedures in replacement include lifting the car off the ground, holding the converter in place, unscrewing the bolts around the flanges, separating the flanges, and then lowering the converter off the vehicle.