Hey guys got rid of the p0032 or 31 code for front upper o2. Now 0431 is popped up. I know for a fact I don't have misfire, or oil seeping into the exhaust manifold. Only thing left is bad upper cats, bad o2, exhaust leak or vacuum leak. I don't believe I have an exhaust leak no sounds of one. Vacuum leak have no idea how to check so any hints on vacuum or exhaust leaks please full me in. I'm having a pressure test done on the cats this Friday to see if cats are bad. I flashed the pcm and it's been two days no code but I know it's coming back I mean it's a jeep ha. Also 106000 miles 05 LJ.