Catalytic Converter: Description and Operation

The three way catalytic converter (TWC) plays a major role in the emission control system. The TWC operates as a gas reactor. Its catalytic function is to speed the heat-producing chemical reaction of components in the exhaust gases in order to reduce air pollutants.

The catalyst material inside the TWC consists of a ceramic substrate. The substrate is coated with a high surface area alumina and contains chemically active palladium.

In a vehicle that is continually misfueled, the lead in the fuel will be deposited in the TWC and completely blanket the catalyst. Lead reacts with platinum to "poison" the catalyst. Continuous use of leaded fuel can destroy the catalyst and render the TWC useless. The addition of lead to the TWC can also solidify the catalyst, causing excessive back pressure in the exhaust system and possibly causing engine damage.

Extremely high temperatures of 1100°C (2012°F) or above due to misfiring or an over-rich fuel/air mixture will cause the ceramic base to sinter or burn, destroying the TWC.

The TWC is designed to provide a long service life. No maintenance is necessary for the TWC. Avoid the following conditions:
^ Driving with a misfiring engine.
^ Continuously running the engine with a misfiring spark plug.
^ Parking or stopping the vehicle over combustible material such as dry grass. The material can be ignited by the high temperatures of the TWC and of the muffler.