Hi all - anyone ever heard of a P0420 code NOT illuminating the CEL? I failed my emmisions test and the guy at the testing center initially told me the system was not ready to test and that made sense because I had just replaced the battery. So I drive about 200 miles without a CEL and I figure I'm good. I go back to the emissions place and I get a cat failure but no CEL. I run my scanner and I get P0420 but still no CEL. Tried resetting the code but it comes right back but never does set off the CEL. I guess its a cat change but I still think its odd that the light never has come on with this code. (the light does work as it comes on at ignition but goes right off). What a hassle!