Hard shifts 1st to 2nd

Saturn Lw300 intermittently Service light but no code stored. Restarting engine works temporarily This started a month or so ago. A few weeks later again and lately 2-3 times. It is a hard shift around second gear always when the car is warmed up and will continue happening until I restart the car, then it's gone for awhile. The service engine light always comes on but no codes are stored according to autozone. Thanks Wayne