so last march I got the p0420 code. Changed out the sensor and everything worked fine.......until 30 minutes ago.... The dreaded p0420 has returned. Before I go replacing the sensor again I thought I would stop by. Is it possible something else is wrong. Today the temp dropped to 30 degrees similar to what it was the first time. Is it possible the cold is causing a problem elsewhere or might I have gotten a bad sensor? It didn't happen until the car was fully warmed up. It seems unlikely that A) the original sensor went bad after only 32,000 miles and B) the replacement went bad after only 10,000. Anyone hear of something similar or am I unlucky?
here's a link to my thread from march for the background
another P0420 thread