Car won't shift into overdrive

The Check Engine Light is on? Did you read the DTCs.

The second link has the answer, the first link says it is a known issue. It is times like this you need the Dealership or a good auto electrician.

Transmission won't shift to third until temp rise

ClubLexus https://www.clublexus.com > forums > 713188-transm...
Apr 1, 2017 - Transmission won't shift to third until temp rise ... The solution is to drive slow and keep rpms at 2.5k and 3k at max till the engine and transmission warm up.
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RX300 not shifting into overdrive. - Lexus Forum Discussion
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Owner of Lexus RX300 with 182000 miles. Recently the ...

JustAnswer https://www.justanswer.com > lexus > 3wsxt-lexus-rx3...
Aug 22, 2010 - Recently the transmission won't go into overdrive. Stays in 3rd gear like when you press the o/d button to do so. When car is cold (live in ...
1 answer · Top answer: Hello and thank you for using just answer! The check engine light is on correct?

https://www.google.com/search?q=Lexus+RX300+will+shift+into+overdrive+once%2C+and+after+slowing+down+it+won%27t+go+past+3rd+gear

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The erratic jumping in and out of overdrive (O/D) on your 2006 Terrano 3GMR with a 3.2L engine could be caused by a few different issues. Here are some possible causes and fixes:

1. Faulty speed sensor: The speed sensor provides input to the transmission control module (TCM) to determine when to engage overdrive. A faulty sensor can cause the TCM to think the vehicle is going too slow or too fast for overdrive engagement. A mechanic can test the speed sensor and replace it if necessary.
2. Low transmission fluid level: Low transmission fluid level can cause the transmission to shift erratically or not engage overdrive. Check the transmission fluid level and add fluid as necessary. If the fluid level is low, it's important to also check for any leaks that may be causing the fluid loss.
3. Worn or damaged overdrive band: The overdrive band is responsible for engaging and disengaging overdrive. If the band is worn or damaged, it may not engage properly. A mechanic can inspect the overdrive band and replace it if necessary.
4. Transmission control module (TCM) issues: The TCM controls the shifting and engagement of overdrive. If the TCM is malfunctioning, it may not engage overdrive or cause erratic shifting. A mechanic can test the TCM and replace it if necessary.

It's recommended to have a professional mechanic diagnose and repair the issue, as the transmission is a complex and vital component of the vehicle.

look for knock sensor codes in the history on the engine computer

One year ago---your check engine light came on
The PO405 code was for an EGR Valve issue
No mention--- if you had that fixed

A Few Days Ago---you get Trac Light on,that is part of
the ABS Braking System
Now that system has to be diagnosed & repaired,not just
continue to use the car,actually make the repair, before
you do some damage or can't stop the car & worse things happen

Changing Trans Fluid---is NOT a FIX for anything,but should
be done on all vehicles every 3 years.

If the Engine Management System isn't working correctly,then
your trans won't work as it should either

You need to be proactive & immediately have any abnormal
operation or check light problems, at least diagnosed in a few days
of noticing them

You need to stop using any car that isn't 100% & have it
repaired as soon as possible.

Not wait weeks or years.
Being 9 years old, the trans may also have it's own issues

Have the vehicle scanned.The overdrive light is like the check engine light for the transmission. There are transmission codes in the ecm if the overdrive light is blinking.

I'm not a lexus guy , but I'm thinking that you have a vacuum leak somewhere.

it sounds like the detent cable that allows the trany to shifts thru its shift points needs to be adjusted - the problem is the year of this car has electronic and manual shifting - so you need to look and determain this or the best bet is to take int a trany shop and let themtake a look

chances are you don't have to replace the computer. the reason i tell you this is because you did not mention that the car is running lousy. no complaints of rough idle or missfire or hard starting. chances are that your engine speed sensor which sends the signal to the computer which then controls the transmission is most likely the culprit.. and it could just bhe that there is a loose connection between the two. if that is ok then your transmission control module is faulty. this is not the main computer, but the gobetween the trans and the ecm.. hope this helps please rate this...thanks(btw....the knock sensors control timing not the trans mission)

Your transmission fluid contain water,thats why the colour of the fluid changed to pink.And of such the clutch is slipping causing the engine to reve up before shifting - Check transmission cooler.