Yellow light came on looks like a engine but in the book its the gas cap was light?

II haven't any problems with the jeep, but yesterday the yellow light cam on looks like a engine but in the book its the gas cap was lite. I drove the car down the street and park, reverse, drive lights were on but should have just been the drive light. When I drove it a little more approx 3 miles I stop and then my car would not go. I put the car in park and then in drive and drove to the mechanic. The mechanic put on machine a code was there and he rebooted the computer, I assume it something to do with transmission. My car is working fine now, I'm very nerves to drive the car?