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I have noticed that temp gauge changes after driving the car for a trip of 1 hour and 30 minutes
So in first 30 minutes of the trip it was between second and third line, while after one hour it was a little above third line, and finally when i reached my destination it was again between second and third line!
I have noticed that temp gauge changes after driving the car for a trip of 1 hour and 30 minutes
So in first 30 minutes of the trip it was between second and third line, while after one hour it was a little above third line, and finally when i reached my destination it was again between second and third line!
Is it thermostat or the ECT?
Didn't you read the temperature using an OBD-II tool?
Didn't you read the temperature using an OBD-II tool?
Again went for a trip of 2 hours during night where outside temp was 18º, but this time took my OBD2 scanner to read the ECT values.. I have noticed that Temp gauge drops only when car is moving, but on idle it reads 77º, while when car moving it reads lower 70º !!
As am seeing, temp gauge is reading the actual values.., so it means ECT is working fine
Is that normal?
attaching below the readings...
After 2 hours of driving the temp should be around 180-190 degrees which would be the cars operating temperature. if it's only reading 77 then dropping to 70 then the car is not heating up properly and thats probably because your thermostat is stuck open. If your coolant was low you would be overheating instead the car is not even getting to operating temp. Does your heat blow hot or warm?
Again went for a trip of 2 hours during night where outside temp was 18º, but this time took my OBD2 scanner to read the ECT values.. I have noticed that Temp gauge drops only when car is moving, but on idle it reads 77º, while when car moving it reads lower 70º !!
As am seeing, temp gauge is reading the actual values.., so it means ECT is working fine
Is that normal?
attaching below the readings...
After 2 hours of driving the temp should be around 180-190 degrees which would be the cars operating temperature. if it's only reading 77 then dropping to 70 then the car is not heating up properly and thats probably because your thermostat is stuck open. If your coolant was low you would be overheating instead the car is not even getting to operating temp. Does your heat blow hot or warm?
180-190 degrees fahrenheit or celsius ?
The temperatures which i mentioned in my previous post are in Celsius, during the day driving the temp needle reads 85 Celsius, what i mentioned is only during night driving
heat blows hot
Originally Posted by Yamae
A slow temperature rise is mostly caused by a worn thermostat. The ECT sensor only detects the temperature. It doesn't have a long time constant. It only has about 10 seconds of it.
As per your old post Do you recommend me to change the thermostat ?
My current highway MPG is 20 only!
I was talking about Fahrenheit so if it's 85 Celsius then the car is getting to operating temp. i would change the thermostat . It's a cheap and easy fix.
As per your old post Do you recommend me to change the thermostat ?
My current highway MPG is 20 only!
The early bird gets the worm. A slow fix damages the car more and looses the money. If I were you, I would enjoy better drive feeling and better gas mileage changing the thermostat quickly. Improved gas mileage would be quickly more than the cost of the thermostat and that $ will be added more and more in the future.
Have a 1993 LS400 with 150K miles. I have changed the temperature sensor about a month ago and did ABSOLUTELY NOTHING to the gas mileage. Still get between 12-15MPG here in California. Basically if your temp needle is moving up to the 35-40% (near the 3rd line) and you get good heat coming from the heater, DON'T CHANGE THE ECT sensor, won't do anything for you!
However two days ago I serviced the car and have the throttle body cleaned plus fuel injector cleaning at the Lexus dealer, after the service the car felt totally transformed! I felt the engine HP has increased significantly and gas mileage has improved to 18MPG!
I think I have finally fixed my bad mileage issue. A dirty engine is very much more likely the main culprit compare to any sensor issue, especially if your car is not throwing any codes.
My engine coolant temperature is always maxing out at the 3rd line (~40%) and will dip down a bit during highway driving in the winter, to perhaps ~35%, between the 2nd and 3rd line. This behavior is absolutely normal and no cause for concern.
Hope this helps you folks with high mileage LS400s.
So after reading this thread, i planned to change my sensor. It was totally bad when i pulled it out, the main problem i had was findig the correct sensor as it has 2 sensors. I ordered one from amazon and it was smalled thn the factory one. So i had to get one from dealership as the sensor was broken and since i have changed it i can see a huge difference in mileage. First my half tank used to stay for 2 and half day of driving on freeway but now i did 5 days with just a little over half gas tank. I am very happy with this. U should change it too.
My OBD diagnostic tool shows coolant temperature 85° Celsius on completely hot engine after long driving. Is it normal for this engine? Because most of other petrol cars is showing 88-92°. Thermostat is new.
By the way, when you are buying thermostat better take old one with you, or at least compare diameters. Because for local shop I gave oem number, they also checked with VIN, but still thermostat was different.
Hi, I am attempting to change this myself with very little mechanical knowledge. I have read the post a couple times and I think I am on the right track but it seems more complicated then removing all the plastic from the front. Can anyone let me know if I am doing it right? Do I have to disconnect these wires? I have to get this part with the wire running through it to get to the ECT correct? I have one side of the spark plug cover? off the engine. I Have to remove the other side to get that plastic cover with the wires going through it. It is under here yes? I think I can see it but I know it could be something else.
07-01-14, 12:31 AM
Am I on the right track?
