Car not shifting

I have a 2000 Lexus RX300 (automatic) and over the last few months have noticed that it sometimes fails to shift gears (gets stuck in fourth gear & mostly on the highway). Sometimes if I stop and turn the car off and then back on, it fixes the problem (but of course I can’t do this on the highway). I took it to my mechanic but it didn’t do it when he test-drove it. Any suggestions?

Have you followed the recommended service intervals for your transmission? Have you checked the transmission fluid level regularly? I would take the vehicle to a transmission mechanic and explain exactly what’s going on with the tranny. They may be able to give you a little more insight once they check it out.

Well I thought I’ve kept it pretty well maintained as far as oil changes, and tune ups and what not. I am assuming the check the transmission when they do that. What about checking/adding fluid and testing it out before I take it in? Or is it best to take it in? I just had it checked out not that long ago and they told me everything else that needed fixed but nothing about the transmission.

I would check the transmission fluid before taking it in. Make sure you follow the correct procedures in your owners manual for checking transmission fluid. Checking tranny fluid is a little more involved than say checking the oil in the engine. If the fluid level is really low then you may have found part of your problem.

I will do that. Thanks for your help!

Something occasionally hangs up …some valve doesn’t move. Changing the fluid may remove the burr or whatever is fouling the proper operation. Consider Auto-Rx (www.auto-rx.com) about 1000 miles before a full fluid exchange.

My trans would get stuck in WOT mode. No shifting until the maximum shift speed. Auto-Rx eliminated it rather quickly.