That code is very common with the 4t65e. It could be the PCS sensor, or the trans needs to be refreshed depending on your mileage. You might want to consider saving up and buying a tranny from
Transmissions
Most shops will charge in excess of $500 for that sensor+install. My thoughts are to just save up and get a refreshed trans which should last you a good while. If you just replace the sensor, you might be fine for another month and that code could pop up again and then that could indicate your frictions are worn.