Oct 5 2009: O2 sensor update:  It happened again for the first time since Aug 3, 2 months ago.  Also it happened on a Monday afternoon right after starting it to go to work.  At the time, I hadn’t started my car in over 50 hours.  If I remember correctly, the same situation was true on Aug 3.  I hope the coming cold weather won’t be exacerbating the problem.

By the way, I was previously mistaken about when the inspection is due.  I though it was due in September, but that was the registration.  I think the inspection will be due in March.

Aug 12 2009: My 2003 V6 Nissan Altima seems to have an O2 sensor that is going out.

I have over 80,000 miles on it, so it’s probably about time for it to go out.  My inspection is due next month, so I don’t have much time to replace it.  Monday Aug 3, the SES / Service Engine Soon light came on.  It was OBDII code 0031.  I cleared the code at around 8:00 that night and as of today, Wednesday Aug 12, the SES light hasn’t come back on yet.  (I hope this will last to the inspection.  O2 sensors are expensive.)

I looked up the OBD2 code in the service manual I have.  It told me there is an open to the heater in the O2 sensor.  It could be a wire as well, I don’t know yet.  If I have to, I’ll troubleshoot it in time to renew the car’s inspection.  I just hope I don’t have to replace 2 of them at once, like I’ve heard you’re supposed to do when one has to be replaced.  This car has 4 O2 sensors altogether.