My es300 v6 lexus wontshift into 4th gear whichis overdrive

SOURCE: Overdrive light flashing on my 1994 Lexus ES300/speedometer quit

I bet money on the tranny speed sensor being the problem- I think NAPA has em for about $100 bucks or so, but that has been a while. Good luck

SOURCE: Overdrive on of 2001 Lexus ES300

you push the button!its on the side of your shifter

SOURCE: transmission won't go into overdrive when engine is hot

Lexus's have a complicated system of electronics that control the function of the transmission.Under normal operating conditions the transmission is controlled by the ecu and by a secondary system called a drivetrain control module. usually when a fault occurs it sends a code to the ecu and the check engine light comes on.
If this light does not come on then typically the electronic modulator is at fault and needs to be replaced.
If the check engine light comes on when the vehicle is hot i need this code to guide u further for the repair.
If u want to attempt the repair , be wary. its messy and takes time to do to do it right.

SOURCE: 2000 es300 lexus auto w overdrive button overdrive 4th gear not work

There isn't anything wrong with your car. This is perfectly normal. I have a 2000 ES300 as well as other people that I know and it operates in the same way. Overdrive doesn't mean the same thing for every car or transmission. In our case overdrive is simply a reference to the top gear which is 4th gear. When you switch overdrive off(which is depressing the button causing the O/D OFF dash light to illuminate,) the highest gear becomes 3rd because you turned 4th gear or overdrive off. The application scenario for this is usually mountainous terrain where a lot of uphill driving makes it more feasible not to up shift into 4th gear while ascending and descending. It will not switch back to overdrive or 4th gear until you re-engage it by turning the overdrive back on or repressing the button. Again, when the O/D OFF dash light is illuminated, overdrive which is 4th gear is off and the highest gear will then become 3rd. It will never shift into 4th gear while this light is illuminated or overdrive is off. When you press the button and the O/D OFF dash light is NOT illuminated overdrive is on and therefore it will shift into 4th gear as usual. This applies to all 97-2001 ES300's and probably any other car you drive tat exhibits this same type of change when overdrive is turned off.

SOURCE: Problem w/transmission Lexus ES300 1999

Is your O/D off? There should be a light under your speedometer, if it says "O/D OFF" than your car wont go to fourth gear. You can turn the overdrive back on on the knob that changes gears, theres a little button on the side. Press it and you should be good.