A catalytic converter operates normally between 550 and 1,600 degrees Fahrenheit with the optimal temperature being about 806 degrees. Pollutants coming through the exhaust system can raise the temperature over 2,000 degrees Fahrenheit, at which point, the catalytic converter can be severely damaged.
Misfiring spark plugs, bad plug wires and leaking engine valves can all lead to excess pollutants. When the catalytic converter overheats, the ceramic honeycomb inside the shell can melt, causing a blockage. This can lead to a sharp drop in performance, and may cause the engine to stall. A hot converter suddenly exposed to cold temperatures, such as cold fuel or snow, can warp and disintegrate.