The check engine light was on in my 2007 Nissan for a few days.

What is your question?

The check engine light has since gone out. The vehicle had lost power & stalled. It started again. A friend used a device to see what the problem was. It indicated a sensor would be replaced. Since the light has gone out, I wasn't certain if there wold still be a problem. Would this indicate a problem or a faulty bulb or fuse?