If you have noticed your Pt Cruiser overheating, don't worry, your not alone. . . . .
Automatic restart. Two cheap tweaks will include changing the radiator cap (it may be faulty, and causing your radiator to malfunction), and/or affect the thermostat and gasket. Handy remote device and plastic window kit (36" max.
Low coolant might be the most obvious culprit here, but be careful when should you are taking the radiator cap off! It is planning to be hot for some time after you shut off your car!.