Hi, I have a 350z 2005 DE Automatic, I use my car in track day.
some days ago, when i use the “semi automatic shift” , the gear starts to enter in Drive automactily.
i don’t know what is happening, could you help me?
what can I do to fix it?

 

Error Codes?

Your manual switch could be out or about to go out

 

So we're clear-
Are you speaking of moving your shifter to the right gate for "Manual Mode?" And then it continues to shift without moving the lever?
As stated above, see if you have codes. If what I describe is accurate you have 2 choices -
1) Start taking things apart, looking for loose fasteners or missing pieces. (or faulty shift switch ).
2) Seek professional help. If you are a novice this may be your best choice. Gl!