So I've had my new LTs and catted x-pipe on my car for about a week and this morning that code popped up. Its P0430 "catalyst system efficency below threshold bank 2"

Question is, will this damage anything, what causes it and how do I fix it?

 

I believe that's caused by the rear O2 sensors finding the new cats to be less effective than the OEM ones. Disabling your rear O2 sensors in the tune would make the code go away, but you wouldn't be able to pass emissions testing. You can also install O2 non-foulers to raise the sensors out of the exhaust stream.

 

no, aside from the check engine light being on, and if you're in a state which does emissions inspection it'll fail.

your new catalytic converters don't work very effectively. The upstream (pre-cat) O2 sensors are used by the PCM for air:fuel management; the downstream (post-cat) O2 sensors are used by the PCM to make sure the cats are there and working. If the signal coming from the upstream and downstream sensors are too similar, you'll get "catalyst efficiency" codes.

either put the stock cats/pipe back on or find something that'll ignore the downstream sensors.

 

Ok, well as long as its not going to damage anything I'm ok with it. I'm putting on a supercharger this weekend and turning off the rear O2s anyway. I don't have emissions testing here in FL, but I put the cats on just in case I moved to a state that does. I'll worry about it then if I need to. Thanks guys.