mjr955201

Hi, I currently have a P1025 insufficient coolant temperature code. From what I have searched, it can be multiple issues;
-coolant temperature sensor
-thermostat
-oxygen sensor

I have a new temp sensor / thermostat ready to install. Where exactly is the coolant temp sensor located?

Has anyone tackled this issue before. The guy at the auto parts store said it was most likely the oxygen sensors, but I have read other things on this forum.

I think I found it, but am not certain. Any help would be appreciated. Need to get the check light off for inspection.

1st picture is where I think the coolant sensor is located. Correct?
2nd pic is the thermostat housing. correct?

Thank you.

Ali SC3

iTrader: (10)

Its probably the coolant temp sensor or the thermostat.
if the gauge on your dash is reading fine then more the temp sensor. if both are reading low then could be the thermostat.
if it was serviced recently half the time its not even the sensor but just the connector on it because the clip can break or the wires can back out from being pulled on (to get the connector off the lazy way).

I dont see how it would be the o2 sensors it doesn't even make much sense really. maybe in some super rare instance I would not be changing o2's for that code though skip that for now.

1st pic that is the location, you want the one with 2 wires. there will be another one with 1 wire that goes to the gauge cluster, well at least on the older models yours is vvti so it may be a little different. coolant in the head and upper radiator hose/radiator will pour out so be prepared for that, either drain the system down some or be ready to do a quick removal and install the new one.

the second pic is a yes also.

KahnBB6

iTrader: (5)

Yes, it's in that area. You've found it. Although since you have a 98-00 VVT-i model I cannot be sure if they changed anything in that area. Probably not but it would be good to check a TSRM.

Also, this may be redundant but at least on the older non-vvt models (possibly on vvt's also) there is the ECU coolant temperature sensor you are going to service... and a separate temperature sensor specifically for the temperature gauge in the instrument cluster.

The way to do it is to put a catch pan underneath the car and wait until it's 100% cold. Then you can go about removing the old one and quickly (but carefully) replace it with the new one as the coolant is spilling out of the port hole.

Don't forget the required OEM crush washer for your new sensor and have a jug or two of new coolant waiting to refill your car. It would be a good idea to burp the cooling system also with one of those special funnels once you start up again.

TheMole did a great DIY thread on this. Read through all the pages for all the notes you will need, including the torque spec for the sensor.

https://www.clublexus.com/forums/per...-i6-sc300.html

mjr955201

Thank you for the quick response. I will change out the sensor first to see if that corrects the issue. Now just have to figure out how to get in there without taking stuff apart.

Luxor

iTrader: (15)

I changed mine a year ago on my 1998 SC300. It has a green end on it. I did not have to remove anything to replace it. It's located under the intake manifold around under the #1 - #3 injectors. I used a deep socket tool to replace the sensor. Don't forget to get a new gasket with the sensor.

mjr955201

ok, the sensor I thought was it has a different connector. So now I am confused.but the electrical connector is different and the nut is much larger on the current sensor, if its even the correct one. It is located just beneath the power steering fluid reseviour

1999 sc300

Am I looking in the correct place, or is it underneath the timing cover? thank you.

mjr955201

well im off to change the thermostat now since I have the new part, because i am totally lost on the temp coolant sensor location currently. maybe it will correct the 0125 code, if not I will be very lost. Will report back w/ pics / results. thanks.