Catalytic converter damage

If the engine control module (ECM) detects a certain number of misfires during 200 engine revolutions, this is interpreted as misfiring which damages the three-way catalytic converter (TWC). The number of misfires that the engine control module (ECM) allows before interpreting it as misfiring depends on the load and engine speed range.

The engine control module (ECM) registers and stores the engine speed and load range and whether the engine is warm or cold when misfiring is detected.

If the misfire stops, the requirements for the engine speed and load parameters must be met without misfiring before the engine control module (ECM) will begin counting down to extinguish the warning lamp and erase stored diagnostic trouble codes (DTCs) for misfiring.