So the P0430 P0420 codes are pretty constant. I will clear them and then they come back after a day or so. Engine runs smooth, no loss of mpg, no rough idle, just the codes. I put new O2 sensors on both sides with non foulers and that worked for a few weeks, but codes came back. This last year I have only been using non-ethanol fuel for every fill up. My local exhaust shop says I shouldn't replace both cats if it's not causing any problems unless I want to pay that much just to clear the check engine light.
Any ideas on what to do? I've done seafoam treatment several times as well.