if your cat is breaking up fix it or you risk damaging your engine. if the cat breaks into pieces, it can get sucked back up into the engine, which would score your cylinder walls. then oil would blow by slowly..causing you to lose oil eventually running out of oil..which would cause you to throw a connecting rod out the side of your engine block!! (happened to my friend and a whole bunch of people)
Anyways, ask on a honda car forum, there is usually a method to clear the light. With my Nissan, it's a case of hitting the gas pedal w/ the car off in a certain combination. You can also hook up an OBDII reader to it and clear the code that way.