I just wanted to report my findings about the V6 and this common code. Do not let anyone talk you into purchasing a new CAT! I have read all over the net about the V6 throwing this code and it points to having the Cat below threshold and replacement is the solution. Because I have thrown this code so many times in the past 5 or 6 years and have easily reset my CEL with my scangauge and kept going I would not recommend replacing. I typically threw the code every 4 months or so and I just reset it and kept going. I have had my emissions in California tested 3 times and all the tests are perfect, in fact in the lowest 10% which would not be possible with a failed CAT. Finally the CEL would not stay off so finally I purchased another rear O2 sensor and spliced up the connector and it is perfect again not throwing the P0420 code. Granted the O2 rear sensor was 150K miles and 10 years old finally gave up the ghost but the code generated points to the cat being below threshold. I checked for leaks and there were none, it was just the 02 sensor. Before anyone purchases a new CAT which at the dealer is over 700 bucks and in California this is the only legal one you can purchase try replacing your rear O2 sensor. Personally before replacing the CAT get a emissions test, this will show a failed CAT.