ok i got the good ol p0420 code.... new cat back (magna high flow cat an muffler) done less then a year ago. so i going to say its the o2 that is bad (bank 1). is there a way to clean the o2 or is it just better off getting a new one. if new one witch one is better brand. thanks 2doorblazer

 

i have the same cat under mine, and the same ol po420 code. i have changed all of the o2 sencors, and still no luck. i was wondering if it had something to do with the catilist in the cat, or that its higher flow than stock. let me do some reserch and see what i can find out. if you figure this out, let me know what you found out