I have had an O2 code for a long time. I just now got the tool to remove it and have the new sensor. But, strangely the code dissapeared for a little while. (the SES went off) It stayed of for a few hours of running. It's back on now, I assume it's the same code, but haven't got batteries to scan it yet. Would this happen or do you think I have some wiring problems? I've had other wiring problems, and I'm just wondering if I might have something else wrong. I could sell this sensor to someone if I know the current one is fine.

Anyway, is this possible or do I just have a bad sensor? Also, what can I do to check the current sensor?

 

I would verify first that the code you are getting is once again related to that problem. If so, an easy way of telling if the sensor is bad is swapping it to the other bank and see if the code follows. Otherwise, I would suspect that there is a wiring/connector issue.