My ECU light went on about 2-3 weeks ago...I checked the codeds and it was my rear o2 sensor. I haven't had time to fix it so I have left it alone. Last night as I was driving I noticed the light was now off. Does the light go off after a certain period of time? Now I do not know if I should replace the o2 sensor or not.

 

Yes it does that. It's going into the cycle mode, basically it's re-testing everything to see if there are other problems and if the problem you have, has been fixed. You will see it come back on in a day or 2. I heard it takes so many start up or miles driven for the ecu to cycle through all the test. I've had my check engine light on for over a year now with a code of the evap canister vent control valve. Had Nissan fix everything possible related to that code, still wont go off but it has gone off for a day or 2 now and then so it can cycle.

 

ahhh ok thanks for the heads up....guess I still have to go pick up that sensor

 

yup you were right on...light came back on....should have written down the mileage and counted number of starts to see what the cycle is

 

Yeah belive me I am becoming a expert with that darn check engine light coming on and off. I have so many problems with my Max its unbeliveable