What is code P0745 on 2002 mercury mountaineer and how do you fix it?

P0745 Is a trouble code for malfunctioning shift selonoid. But be careful as it may not be the selonoid at all. There is a problem with these transmission breaking the band for 3rd. I would advise to you that unless you are experenced in transmission repair I would find someone who is. you can e-mail me with any other questions at diamondpvc1@gmail.com and I will try to help you.