Catalytic Converter: Description and Operation

PURPOSE/OPERATION
The catalytic converter is a three-way catalyst that removes CO, HC, and NOx from the exhaust. Optimum performance of the catalytic converter is obtained, with a fuel-air mixture ratio of 14.7 to 1 ± 1%, and exhaust gas temperatures between 400 to 800 degrees C (750 to 1500 degrees F). Engine malfunctions such as misfiring can result in exhaust temperatures exceeding 1400 degrees C (2500 degrees F). These extreme high temperatures can cause the substrate to melt, destroying the converter. The use of leaded fuels will coat the catalyst preventing catalytic action. Excessive oil residues in the exhaust have the same effect.