My car keeps throwing a CEL for a PO420 which means the cat is not working right. The deal is I just had my new Megan Exhaust, and CA 2.5 DP put on with a high flow cat. I am taking it easy on the car to allow carbon to build up on the cat so it breaks in. Could this just be going on right now because the cat is brand new and not broken in yet??? If so do you think it will go away after a few hundred miles once it breaks in?? Any help would be apriciated.

 

my car throws that code all the time and i had my hi/flow on for about 8mnths i just erase it with my dash hawk

 

So far it has thrown it about every twenty miles or so, but I just clear it with my inteceptor. I do not notice any changes in performance, but I have not got on the car yet eaither. I should wait around 2-300 miles for it to break in right?

 

i waited 500 and i still got the code

 

I still get the code once and a while especially when I go WOT frequently. Just the name of the game, I guess.

 

it seems to be the high flow cats that do it though, just a cat back isnt really gonna throw anything

 

Yeah, I new it was just the high flow cat. Just wanted to make sure it was normal. When you have the CEL does this seem to affect the perfomance in any way? I would not know yet because I am not taking the RPM's over 4000 until it is broken in. I also guess I will give it 500 miles until I get on it just to be sure that cat is OK.