Hi! My 2005 LS430- approx 110,000 miles- when turned on, revs/idles between 1200 and 1500 and won't go down until I put it in gear. When I put into gear, it generally falls down to about 900/1000.
I live in a pretty warm state, so it's not a case of cold weather setting in. Also, when started, the idling sounds higher pitched than usual before it drops. Never happened like this before about 3 weeks ago. Any ideas?
Thank you!
J.

 

My money would be on a faulty coolant temperature sensor.

​​​​​​My old 95 LS400 did this exact thing, where it was idling way higher than it should have because of a bad sensor basically telling the computer that the engine was cold at all times, so it was stuck at the high idle as if it was just fired up in the winter.

I'm not sure about the 3UZFE, but I know the 1UZ in the LS400s had two sensors for coolant... one which sent information to the gauge cluster temperature reading, and the other for the ECU to calculator the fuel tables and idle speed.

 

Thanks for the reply- is the sensor something accessible/replaceable?

 

Yes. It's very easy depending on where it is. On my 95, it was right on top of the motor next to the thermostat. Just an electrical connector, a socket, and a little bit of dripping coolant during the change.

I'm trying to post a picture of what the sensor looks like, but my phone won't allow the photo upload to progress past 90 percent right now for some reason...