I, too, had the P0430 code intermittently for about 1 1/2 years. It would come on for a couple of days then go out for a few weeks, then on for a couple of days again. The engine seemed to run fine and I didn't notice any issues with the engine. However, as time passed, the CEL stayed on longer and longer and I noticed that my fuel economy was getting worse. I had, also, gotten the P0420 code a couple of times. I got a scanner and found that the Long Term Fuel Trim in Bank 2 was high (positive). Bank 1 was elevated, but not as high as Bank 2.
When I brought the Acadia to my mechanic for an unrelated issue, I asked him to check it out. He verified the fuel trim issue and used a scope to look at the valves.. He told me that I had extensive carbon build up on the tops of the valves which was not uncommon in our direct injection engines. The carbon buildup was causing misfires , which, in turn was allowing unburned fuel to pass into the exhaust which damaged the catalytic converters. He recommended doing a chemical clean of the top of the valves. I let him do it, but he said it only cleaned about 50% of the carbon build up. He said the best way to completely clean all the carbon build up is to do a power walnut blast cleaning.
The CC for our Acadias cost about $700 each for the parts alone.
If you need to replace your CC, first determine why the CC was damaged to begin with or you will most likely damage your new one again.
2016 Buick Enclave Premium AWD Ebony Twilight Metallic w/ Choccachino interior , 7 pass. , Sunroof and Trailering Package
2010 GMC Acadia SLT-; AWD; Quicksilver w/Ebony Leather, 7 pass. seating, Duel Sunroof, DVD, Nav.