I tried to search for this question but -

If you reset the Check Engine Light by disconnecting the battery, and it stays off, does that mean the original problem is gone?

Or is it still there, and the light is waiting for the next problem?

 

Just because a Check Engine light is on does not mean the problem that caused it is still there. And if the problem is not there, after so many cycles of the ignition, the light will turn off on it's own. Also if you reset the light, it does not mean the light will not come back. If the problem is intermitton, the light will stay off until it's caused again. It would have been best to have the code scanned to see what set it off. That way after it's cleared if the same code is set down the road, you then have atleast some idea you need to have that specific problem fixed, b4 it gets worse.

- Dae