Does not shift and check engine light turns on when transmission gets warm

Let's start with codes. This sounds like a shift solenoid issue but we need to see what codes it is throwing before we go any further. That will tell us what the potential issue is or at least the system.

If you cannot pull codes then just stop by a parts store as most of them offer a free service of pulling codes. Clearly they want to sell you the parts that you will need which is why they do it but we need to start with the code and then do some diagnostic work to figure it out. Thanks