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Ambient (outside) Temperature Sensor 2000 Rx300


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Hi Guys,

I am in Canada but my girlfriend's 2000 RX300 thinks we are in the North Pole sometimes.

We recently picked up this RX300 from the original owner who serviced it religiously at Lexus of Calgary. The owner made us aware of the Ambient (Outside) Temperture Problem when we bought it.

In a very random fashion the ambient (outside) temperature read out on the information center display will drop to -37C and stay there for a while before returning to within 5 degrees less than the current ambient temperature. Sometimes it wont give any reading and will just give two dashes instead. It seems to occur after going over or into a steep bump or dip.

The Lexus dealer here has told the prvious owner they are not sure how to fix it. I think they have tried to move it around because I think I found it hanging losely in the driver's side fender when I was replacing a park lamp bulb. Is that where the ambient temperature sensor is located or have I just found another faulty or lose part?

Otherwise my girlfriend loves her Lexus and everything else works like a charm. I was just hoping for some feedback on this forum as to how to address this issue. Should I just buy a new sensor or mount it in a better location? IS there something else I am missing?

Thanks for any help in advance.


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  • 8 months later...

I have a 2003 GX470 with a VERY similar problem. Ambient temperature reading is -22F and slowly progresses up to close to actual. Then, without any other indications, it is back down at -22F. This is a real problem in the Southern US, as the AC does not cool "automatically" when it thinks the outside temperature is so low. AC works fine if I put it on COLD MAX, but other than that, no luck.

Did you find out the cause?

Anyone else?

I have checked the actual sensor, even replaced it but to no avail. Any guidance is greatly appreciated.


Okay, 3 hrs later, problem solved. Found out that when an aftermarket stereo was installed, one of the connections was loosened. Actually the connection may even be a grounding point. It was located under the wood panel on the left side of the center console. About 2/3rds the way down, there is a brass colored bolt over a white plastic piece. Under this is a bunch of wires all coming into a connection point. I found the bolt was very loose. As I took it and shook it, I saw the display for the temperature actually turn off, then return with a low negative number, and go off again, come back with correct temperature, etc... Ah ha, my problem point. Tightened up bolt. Immediately got proper temperature. Whew. Happy to have A/C working again!

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