The computer test showed I have a bad oxygen sensor. I can have the check engine light turned off but will it pass an emissions test in CT without having it replaced?

Which oxygen sensor is bad?

I've been told that it's possible, but you will have to drive 100-200 miles with the Check Engine light off before having the car emission inspected. Apparently, the car's computer has to recognize that it wasn't just a mis-read.

Still, that is no guarantee that it'll pass.

Does the light come on again after a reset? If yes, how soon after (in miles)?

Yes, you will need to drive the car for at least 100 miles before the computer resets and the car can be tested. You might consider doing a trial run(s) first before bringing it in for the actual inspection. See if, or how long it takes for the check engine light to turn back on. Again, no guarantee it will pass.

My Passat had a minor emissions issue that set off a check engine light. Cleared the code, it never returned and it passed the Mass inspection.