01 Maxima; p0420 Check engine light ( cel )

[AFelix]

01 Nissan Maxima, P0420, any help would be great.

[NISTECH]

Hey Felix, ANother code huh? Did you have the ECM reprogramed when you had the O2 replaced? If you did you likely have a bad bank 1 cat convertor. Pretty common on the Max. If you are under I think its 70K miles it should still be convered under warranty here in california. If you didnt have the ECM reprogrammed then , There is a reprogram for that code as well. If you had it done with the O2 replacement then you recieved the updated program and the cat is probably no good.