After many many hours spent rattling my brain on a navigator, here s my two cents. Fix all engine code problems before trying to fix the transmission. In my case, I was getting a p1719 along with two lean codes. It threw my transmission into limp mode after driving 15-20 minutes, everytime. Turned out to be a failing fuel pump. The only way to test was to check fuel pressure; it was at 49 psi when it should be 65-72. Changed the fuel pump, and limp mode and all engine codes went away. The computer modules on these cars are very strict and at any risk of causing harm, will throw your transmission into limp mode.
Wednesday, November 1st, 2017 AT 4:42 PM