Trans. problems

I have a 1999 grand prix gtp and my ? is I notice today when I was driving. The trans. would shift hard into 1st then 2nd and so on. I shut the car off and drove down the road again and it did not do it. Then it did it again. So what I was wondering is could it be a sensor or is it something major ? Please give me your input. also the trans. fluid is fine and does not smell burnt.

I have a 1999 grand prix gtp and my ? is I notice today when I was driving. The trans. would shift hard into 1st then 2nd and so on. I shut the car off and drove down the road again and it did not do it. Then it did it again. So what I was wondering is could it be a sensor or is it something major ? Please give me your input. also the trans. fluid is fine and does not smell burnt.

How many miles on your GTP? This is a common problem on the 4T65E tranny and "W" bodies. Do you get any type of whining sound, etc. Might want to get it to a reputable tranny shop and have them test it to find out why there may be high line pressure. Plus have them scan for odb-ii manufacturer specific tranny DTC fault codes such as P18XX, etc.
Maybe from that you can determine whether it is something major or minor. Good luck!