Transmission Failsafe, code P17E1

Hi, Ive finally had my first real problem after owning my car for 4 year. My transmission has gone into safe mode 3 times in the past 6 months but each time after a restart it would be good. Last month it did the same when i got pulled over after driving about 300 miles so i restarted and drove the remainder of 400 miles with out any issues. Drove it back another 2-300 while out of town and back home about 800 miles without issues. I have been driving it about 100 miles daily since then and no issues. Yesterday drove around town and noticed when i shift reverse to drive more often is when i get the issue. It started to give me that same error and not move the car and for the first time engine light came on. I scanned it and it gave me a error code P17E1. I went ahead and did a little of my own troubleshooting after reading forums with no luck. Voltage is about 14-14.5v started and 12.3-12.5v off. What else can i check before taking it to the shop? Car has about 40k miles. It is shifting fine today and shifting was great before this issue also.