I have a 2004 350z touring which I purchased a few months ago. The SES light says I have a bad 02 sensor. I had it replaced by Pep Boys but within a few minutes of driving the light came back on. I took it back to them and they told me that I may have to drive it a while before the readiness monitors cleared and then they reset the light. The light came back on and I had it reset again and tried driving it for over a week, but the light didn't go away. I took it to the Nissan dealership and after their "diagnostic" they told me I needed to replace the same sensor I just had replaced (rear passenger or bank 1 sensor 2). I took it back to Pep boys and asked them to check and see if maybe they installed a bad sensor. They tested all my sensors and said they worked fine and that perhaps something was wrong with the ECU which Nissan denied that as being the culprit. I cannot pass emissions because of this nagging problem and I don't want to have Nissan replace the sensor only to have the light come back on again. I am going to try doing the official drive cycles to see if maybe the light will clear after that but otherwise I have NO idea what to do. Any suggestions or advice would be greatly appreciated!!!

 

Did you fix the problem? Im having the same problem

 

Just got it fixed this week as it turns out. At first Nissan told me to try replacing sensor again but after further inspection it turned out that the relay in the ecu to the sensor had burnt out. Had to replace ecu. $1400 parts and labor. Light is gone now. Good luck to you with the repair. Hopefully it is something simple and inexpensive.

 

One final update. I drove the car around for a couple days after the ecu was replaced and the light never came back on. I took it today and passed emissions!!!