check eng / lost 4th gear on highway?

i have a 98 cavalier 2.2l rs model.

i was driving on the highway the other day, and the c.e.l. came on, and i notices the last gear was lost *automatic trans*

i pulled over, poped hood, and chekced fluids, and noticed the trans fluid was a little low.

could this have caused it? i started back up, and it was gone and trans was fine, but it happened again today, so i was wondering what it is.

(it also went away again today..)

any ideas?

I'd read the code to see what it's concerning. I know that some codes will cause the trans to disable overdrive, but you don't really know anything w/o a code to start with. let us know what you find out.

but in the meantime, yes, definetely top off that fluid