get a new catalytic converter. they can not be cleaned. that code means the chemical reaction that is supposed to be happening inside the cc is not happening the way it should. JUst get a high flow cat and be done with it. also another option if you just want to turn off the check engine light is too remove the rear 02 sensor. zip tie it to outside air and just plug the 02 bung in the cat and reset the light. wont give you anymore problems after that. any questions pm me.