I recently put my 2.5 back together after a snapped timing belt incident (good old Gates). I had a spare set of heads that I had valve reground. It runs well and has new Aisin timing belt components. Prior to this event, I had been P0420-free for about 8 months (finally tracked down an exhaust leak at Y-pipe). After a few hundred miles on the re-hab’d engine, the P0420 is back. I tried clearing it and it came back in 80 miles or so. Romraider logs appear to show AF and rear O2 sensors working properly but I noticed some odd rpm behaivoir on some of the logs. I think rpm is tied to the crank position sensor and I didn’t even remove it (but I did disconnect the harness) when doing the heads. Could this be the cause of my P0420? I’m not getting a crank position code. I am going to double check for exhaust leaks but could my CPS be going bad?
