Hi, my auto transmission suddenly stopped upshifting.

It will start in low gear while in drive but not shift to any higher gears. I have to put the car in nuetral when I attain the correct speed, then drop it back into drive for it to shift.

I have to do this repeatedly to shift through each higher gear.

It will downshift as I slow down or stop, but not upshift as I speed up.

I'm wondering if anyone hear has had a similar problem and what the possible fix may be. Any information would be helpful.

Thanks!