I hate to bring this back but I NEED help with this problem.

I am having the same problem, car is stuck in 2nd gear. Now the speedometer works FINE, but the car won't go above 2nd at all. And I don't think it's internal because the trans. fluid is fine and it did work in cold perfect and then when it got warm again stopped working. If it was internal I don't think the weather would matter. So I bought an input speed sensor at advanced auto, and I'm going to put it in once the weather warms up in a few days.

Before I put it in, does anyone else think my problem is the speed sensor?

 

My financee strat wouldn't shift and it was a busted speed sensor, keep in mind I beleive there are two sensors on your tran, one on either side, make sure the dealer gets you the right one

 

Here's a little light reading on our A604 trannies ...
http://www.allpar.com/fix/trans.html