05 Sebring "chugs" while driving

took it to the only parts store open on Sunday in my small backwoods town. Light went out turning into the parking lot. Store clerk says “can’t read an error code if the light isn’t on”. I asked the question “Oh, then the code isn’t stored in there somewhere”? Guys says “nope but if you think that’s it I can order the part and have it here tomorrow.” “Na”, I say. "I’ll try it at the other store tomorrow."
Thanx for the input. Hopefully the next store can help me.