The catalytic converter is an important element of a modern vehicle exhaust system. It uses the catalytic action of precious metals to convert combustion pollutants into naturally occurring gases, reducing emissions of hydrocarbons, nitrogen oxides and carbon monoxide to low levels.
The minimum temperature at which a catalytic converter begins to function, called the light-off temperature, is 600-700 degrees F.
Vehicle manufacturers usually minimize the distance between the engine and catalytic converter. This reduces the time required for the converter to reach operating temperature, which in turn reduces cold-start emissions.
The ideal operating temperature range of catalytic converters is 900-1,000 degrees F, although they can, and often do, operate above this range.
However, when a converter operates above 1,300 degrees F for prolonged periods, catalysts and converter components begin to melt. The result is a gradual and usually permanent degradation in performance.
A converter temperature can rise dramatically when an engine is badly malfunctioning or for some other reason producing an excessive amount of heat and pollutants. In such cases the catalyst temperature can exceed 2,000 degrees F. When this happens the converter becomes deactivated and conversion efficiency approaches zero.
