An overheated catalytic converter is often the result of excess hydrocarbon (HC) in the exhaust stream. This will occur if raw fuel is introduced directly into the converter, usually as a result of a problem with the fuel system or the vehicle’s ignition. Improper ignition timing fouled spark plugs and/or air pump failure are the usual causes. This is why your catalytic converter becomes red hot. The normal average temperature of a catalytic converter is between 650 and 900 degrees celsius.