04 Tranny

I have a 2004 Sunfire. Whats going on is after an hour of driving it, it shifts real hard going into 1st to 2nd. I have no CEL. I took it to Auto Zone and was unable to pull any codes. I took it to the tranny shop and they dove it around on the computer and stated it might be a sensor.

It sounds like its shifting to early. I can turn the car off then back on and its fine for about 30 mins.

anyone know what it could be?

its a automatic tranny with 101,000 miles.

How often do you flush the transmission fluid and what condition is it in? On a FWD car it should be done at least every 50k, 30k is best. There should be no burnt smell and it should be red (not burgundy, brown, or black).

ETS OFF light on?

Tranny fluid is red and was flushed not to long ago. No lights are on.

Hmm.... with no errors being thrown its hard to give you any advise or tell you where to start. I've dealt with the same problem but mine was throwin an error when it was an auto. A simple vacuum leak in these cars can cause the tranny to shift hard. One of the many reasons I've converted mine to a 5 speed, much easier to deal with and internals are easy to be swapped out if they fail.