I have a 2000 Maxima.My ses light came on for code 0420. I took the vehicle to my local nissan dealer, and he informed me that any repair would not be covered under warranty, since the car is over 8 years old,according to the service date. I know there is a service bulletin for re-programing the ecm, which i plan on doing first. I own an authentic nissan factory repair manual, and it provides a procedure to check the 3 way catalyst functional status. In case if the re-programing of the ecm does not correct the problem, and the 3 way catalyst test fails, does anyone know the part # for the catalyst for a 2000 maxima (it has the california emissions label under the hood), how much the part costs, and if anyone has experience on removing and replacing one? If anyone has any other suggestions, i would be very appreciative of your opinion. Thank you for all and any help, and i will update any findings for any future reference.