When i got my 98 non calif. maxima it put up a knock sensor code, and a slow response right bank o2 sensor code, i changed the knock sensor and that code went away, as well as the o2 sensor code. i was still getting bad gas mileage so i decided to still replace the right bank o2 sensor, i replaced about 600 miles ago and now the same o2 sensor slow response code started flashing today.

i looked through the forume and it appeared to me that the right bank is the one closest to the firewall, so thats the one i changed. anybody have any opinons?? or know what could be doing this?

 

Just this past Monday, my SES light came on. I went to Autozone and they pulled the codes. P0325 (Knock Sensor) P0420 (Catalyst efficiency below threshold for bank 1) in other words, the main cat.

I debated whether or not to just fix the problems or not as my car had just passed emissions a month ago. I had them reset the codes 2 days later and 4 days and 75 miles later the light remains off. I don't know if the codes are still there...they very well could be if you hook it up to the OBD-II scanner but the SES light is gone, which makes me feel better.

My dad had the same problem on his 99 Toyota Solara when the CEL came on. He brought it to the dealership (car was still under warantee) and they said that after 3 hours of diagnosing the problem it "could" be the main cat. He was having the same symptoms and after resetting the light it never threw the same codes again.

So, if I were you I would just reset the SES light and hopefully the car will pass the emission tests for your state.