I have a 2003 Cavalier and the check engine light will come on and stay on for a few weeks and then go back off. It does this all year long. The computer says it is an O2 sensor, but if it was that I think it would stay on all the time. Someone else had said it could be a wiring harness. If anyone knows anything else, please let me know. Thank You.

 

The o2 could be slowly failing, the computer might be adjusting to it and then it goes out of range again.

 

What is the actual code?