Now that I'm posting I bet my CEL comes back on. In order to narrow down a P0420 code I swapped downstream O2 sensors and cleared the code. It's been 8 days now with a 400 mile round trip to Reno in between. I even took it to get smogged for my registration, it passed. My conclusion: Bad connection on the sensors. A question though. I had a pre-test on the smog and everything passed with flying colors but on the official test the NO was close to the high limit. Why?
