I installed Mac midlength headers with cats and Y-pipe about 6 months ago. Now I've got a constant SES light with code P0430..bank 2 catalyst failure. According to the mechanic at my dealership this code most likely means that the passenger side cat, being an aftermarket product, isn't operating within the parameters that the computer is programmed for and as a result the aft O2 sensor is sending a voltage signature to the PCM that indicates a problem on that side. I believe O2 sims would fix the problem, as would a computer re-tune--maybe--- but I'd like any responses from you folks that have had similar experiences to offer any other suggestions that would be cheaper without "rigging" around the problem. Thanks in advance !!

 

I agree with you that O2 simms should solve your problem. Make sure to reset the code after you install them.




AAAAAAAAARRRRRRRRRRRGGGGGGGGGGGGHHHHHHHHHHHHHH

It's nice to see that we still have a frikkin' 90 second flood control. Now I've got to sit here and continue typing stuff to kill time waiting for the 90 seconds to pass. As sure as I go try to submit again, it won't quite be 90 seconds and when I come back here the 2nd time, the reply that I posted above will have been erased and I'll have to start all over.

<rant off>

 

Yeah....O2 sims....cheapest, easiest fix. The drivers' side was frustratingly tight, but within 2 miles the light blinked out------DONE!

 

I installed the dual cat mac setup on my car, and a month later, I had the same code. I called mac, and the rep said the same thing as your mechanic. I bought a single o2 sim to resolve the issue.
As a side note- I thought it pretty fackin lame that I had to buy sims w/ emissions legal headers/dual cats...Next time I'd buy Hooker Longtubes.