Hi All the Lexus and car gurus out there,

When and if the coolant temp sensor is bad or non-functioning, what are the symptoms??
Will the temp gauge not respond at all (it bottomed out)??? What other warnings it trigger (check engine, check VSC and main red triangle light on)???
I had and have owned and worked on number of Lexus vehicles but never had this issue.


Thank you so much and any input is appreciated, including location of the unit..

2003 Lexus RX300 (160k)
2005 Lexus LS430 (35k)
1997 Lexus EX300 (253k)
2012 Toyota Prius V (28k)

 

Just had my coolant temp sensor replaced about 2 months ago. I first discovered the problem when I noticed the gauge would read very low, pretty much close to the bottom even after a hour or so of driving. Soon enough my "check engine" and "check vsc" light came on along with the main red triangle light. The code came up on the reader as P0128.

Description of code here:

"This means that the engine's PCM detected that the engine has not reached the required temperature level within a specified amount of time after starting the engine. The intent of the P0128 code is to indicate a faulty thermostat. Similar codes: P0125

In determining the engine did not reach a "normal" temperature, it takes into account the length of time the vehicle has been running, the intake air temperature (IAT) sensor reading, the engine coolant temperature (ECT) sensor reading, and the speed of the vehicle."

hope this helps.

 

Hi there,
Thanks for the reply.
My ODBII code was P0118. Other than that, all the symptons are same.
Now I need to locate the unit and replace it.

Thank you for your reply and I will keep you posted.
BTW, do you know where it is on the engine??
Mine is 2005 LS430.

Thanks.

cy

 

Mine is the same year but I had my mechanic handle it...Perhaps this may help


http://lexus.sewellparts.com/oem-cat...S430-2005.html

 

Thanks again and I will post follow-up on this.

cy

 

Finally resolved the issue.

Symptoms were as below:

Hard to start when the battery was not suspect and ran a bit rough.
Coolant gauge bottomed out even after car ran for a while.
Electric fans come on and stays on immediately with the car's engine.
CEL, VSC, Trac Off lights was on with code P0118.
Red triangle light was on.

culprit:

a rat or mice got on top of the engine, under the plastic cover and chewed its way through thin protective sheath and cut one of the two wires from the 'coolant temp sensor'

solution:

soldered the wire and ordered a used pic-tail connector, reset the ODB code.

called the dealer and it says "have to order entire engine electric wire harness" and I didn't even ask how much.

Thank you all for your input. My car runs like a Lexus now.

cy

2005 LS430 (31k)
2003 RX300 (160k)
1997 ES300 (253k)
2012 Prius V (25k)

 

Thanks for the update

 

Good evening I have a 2011 GS 350, I replaced the temperature sensor on the engine block and also the thermostat I'm still getting a P0 128 code, is there another sensor on the radiator or somewhere if so does anyone have a diagram of the location or resolution