P0430 code
 

I have a 2004 cts 3.6 liter.The p0430 code keeps kicking on the check engine light I can reset the light and it will stay off two or three days but come back on sometimes it only stay off for a day any suggestions on what the problem might be any help would be greatly appreciated

It's probably a bad 02 sensor rather than the cat itself. But the cats on the cst can become clogged so check also.