P0430 cats and o2 sensors all replaced

[Mizz0313]

2007 Yukon xl

P0430

Got this code after motor rebuild afm deleted and chasing down a few o2/ misfire codes once all was done. Truck seems to drive fine I’ve put over 1000 miles on it since rebuild. My scan tool shows a really low count of misfires from time to time on a cylinder or 2 but it doesn’t set a misfire code at all. This is the only code I’ve had I have just recently put new cats on and drove 500 miles after clearing code before it came back. All o2s are new and denso only. Plugs and wires were replaced when motor was put together. No other codes whatsoever. Any insight on this is greatly appreciated. Only monitors that are currently not ready for emissions is o2 o2 heater and evap. I changed cats and have been driving it since to get ready for emissions but after 500 miles and no codes the p0430 came back.

 

[swathdiver]

P0430 is a bad cat. It can also set on a new cat but usually within the first 100 miles as they break in and burn off oils. Try swapping your downstream O2 sensors just to rule them out. But my experience has been, if it's setting a code for a cat, it's a bad cat. Someone put on a new cat on my truck before I bought it and it died before the OEM one. Now have Magnaflow cats and Y-pipe. Upstream and downstream O2 sensors are different PNs.