DIY: Engine Coolant Temperature Sensor Replacement- 2jzge I6 SC300
07-07-09, 09:26 AM
#1
DIY: Engine Coolant Temperature Sensor Replacement- 2jzge I6 SC300
Well after replacing the engine coolant temperature sensor on my friend's 1990 Camry and seeing the recent threads on the 1UZ-FE, I decided to change it on my 2jzge 1993 sc300. My sensor was probably original and the new part is not too expensive so why not? 
I used the following:
Duralast (Autozone) part number: SU4007
Price: $29.99
If you want to use Toyota:
OEM part number: 8942220010
MSRP: $63.13
Online: ~$42 - $52
Many Lexus/Toyota vehicles use the same coolant temperature sensor so it should be easy to find.
PURPOSE
"The engine coolant temperature (ECT) sensor measures engine temperature by sensing water temperature. The ECM uses this information for determining the proper air/fuel mixture for all conditions." -via alldata.
If you know how to test it then refer to this:
LOCATION
Green colored harness located under the front intake runner going into the block.
Hope 93MSB doesn't mind me borrowing his pic from here: https://www.clublexus.com/forums/per...-95-sc300.html
TOOLS NEEDED
-Ratchet and extension(s)
-Deep socket 19mm (Make sure it fits over the harness side of the sensor and reaches the bolt. I tested it on the new sensor first.)
-Drain pan (coolant will pour out)
STEPS
-(optional) Remove lower shield under the engine.
-(optional) Place drain pan under car because coolant will poor out once the sensor is removed. It may get messy so have some rags/paper towels ready to soak up excess coolant.
-(optional) If you have a container or pan that will fit under the sensor then it will be easier than removing the lower shield.
-Unplug harness from sensor. The area is pretty tight so I reached under with my right hand to press the release tab and used my left hand to pull on the harness. Came off easily once I got the technique down.
-Slip the deep socket 19mm over the sensor. Again, the area is pretty tight so it may take some wiggling around to get it on the bolt part. There were several times when I thought the socket was on the bolt, but it was only over the harness plug. Just keep pushing in and rotating the socket slowly until it catches since it is a snug fit.
-While removing the sensor, coolant will start pouring out. Have the new sensor out of the box and ready to install. You can also temporarily plug up the hole with your finger as you reach for the new sensor.
-Screw on the new sensor, tighten, and plug the harness back. Sorry I do not have the torque value, but just make sure you don't overtighten since the part is aluminum. Also, make sure it does not leak.
2/2/16 Edit: Tighten to 14 ft/lb
RESULTS and THOUGHTS
-As far as physical appearance, the old sensor did not look too bad after wiping some of the gunk off. It may have still worked fine.
-I have not noticed any significant performance gains in the last week since, but it seems to accelerate a bit easier. It can just be in my head though...
-I hope that it will improve my miles per gallon (mpg). I am still on the same tank so I will report back with any results.
UPDATE: 7/25/2009
-Here is my mpg log with brief descriptions. I'll let you guys decide if there are any differences after changing the sensor
PICS
Old sensor with some gunk
Old sensor after wiping off gunk
Reference threads from the 1UZ-FE community:
https://www.clublexus.com/forums/per...placement.html
https://www.clublexus.com/forums/ls4...ange-pics.html
I used the following:
Duralast (Autozone) part number: SU4007
Price: $29.99
If you want to use Toyota:
OEM part number: 8942220010
MSRP: $63.13
Online: ~$42 - $52
Many Lexus/Toyota vehicles use the same coolant temperature sensor so it should be easy to find.
PURPOSE
"The engine coolant temperature (ECT) sensor measures engine temperature by sensing water temperature. The ECM uses this information for determining the proper air/fuel mixture for all conditions." -via alldata.
If you know how to test it then refer to this:
LOCATION
Green colored harness located under the front intake runner going into the block.
Hope 93MSB doesn't mind me borrowing his pic from here: https://www.clublexus.com/forums/per...-95-sc300.html
TOOLS NEEDED
-Ratchet and extension(s)
-Deep socket 19mm (Make sure it fits over the harness side of the sensor and reaches the bolt. I tested it on the new sensor first.)
-Drain pan (coolant will pour out)
STEPS
-(optional) Remove lower shield under the engine.
-(optional) Place drain pan under car because coolant will poor out once the sensor is removed. It may get messy so have some rags/paper towels ready to soak up excess coolant.
-(optional) If you have a container or pan that will fit under the sensor then it will be easier than removing the lower shield.
-Unplug harness from sensor. The area is pretty tight so I reached under with my right hand to press the release tab and used my left hand to pull on the harness. Came off easily once I got the technique down.
-Slip the deep socket 19mm over the sensor. Again, the area is pretty tight so it may take some wiggling around to get it on the bolt part. There were several times when I thought the socket was on the bolt, but it was only over the harness plug. Just keep pushing in and rotating the socket slowly until it catches since it is a snug fit.
-While removing the sensor, coolant will start pouring out. Have the new sensor out of the box and ready to install. You can also temporarily plug up the hole with your finger as you reach for the new sensor.
-Screw on the new sensor, tighten, and plug the harness back. Sorry I do not have the torque value, but just make sure you don't overtighten since the part is aluminum. Also, make sure it does not leak.
2/2/16 Edit: Tighten to 14 ft/lb
RESULTS and THOUGHTS
-As far as physical appearance, the old sensor did not look too bad after wiping some of the gunk off. It may have still worked fine.
-I have not noticed any significant performance gains in the last week since, but it seems to accelerate a bit easier. It can just be in my head though...
-I hope that it will improve my miles per gallon (mpg). I am still on the same tank so I will report back with any results.
UPDATE: 7/25/2009
-Here is my mpg log with brief descriptions. I'll let you guys decide if there are any differences after changing the sensor
PICS
Old sensor with some gunk
Old sensor after wiping off gunk
Reference threads from the 1UZ-FE community:
https://www.clublexus.com/forums/per...placement.html
https://www.clublexus.com/forums/ls4...ange-pics.html
Last edited by TheMole; 02-02-16 at 08:29 PM. Reason: grammar, spelling, formatting
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2jzjim (02-04-18)
07-07-09, 09:42 AM
#2
nice thread mole i was going to change this sensor myself when i ws having tranny problems this is one of the sensors that the ecu reads off of for transmission o/d engagment. i will subscribe to this just incase i i want to change it when i change to my new aluminum Rad
07-07-09, 02:19 PM
#4
The diagram of the head is incorrect. It shows an oil pressure sensor located to the right of the temp sensor. That is the location of the second temp sensor. There are 2, one (2)wire for the gauge cluster and one single wire for the ecu. The one you changed was for the gauge cluster.
The oil pressure sensor is located on the block. fyi
The oil pressure sensor is located on the block. fyi
07-07-09, 04:23 PM
#6
The diagram of the head is incorrect. It shows an oil pressure sensor located to the right of the temp sensor. That is the location of the second temp sensor. There are 2, one (2)wire for the gauge cluster and one single wire for the ecu. The one you changed was for the gauge cluster.
The oil pressure sensor is located on the block. fyi
The oil pressure sensor is located on the block. fyi
Where is the single wire one located?
07-07-09, 04:57 PM
#7
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Duralast is basically a knock-off brand and i've bought/gotten enough of their stuff before to be able to see the difference between it and nippon denso or sumitomo.
I mean here we are talking about a part were few ohms difference can seriously affect your engine. It just doesnt make sense using a part that isnt going to meet the oem specs you are trying to get to.
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07-07-09, 05:03 PM
#8
Working doesnt mean working well. I mean the oem sensor everyone replaces still works, but that doesnt mean it works well.
Duralast is basically a knock-off brand and i've bought/gotten enough of their stuff before to be able to see the difference between it and nippon denso or sumitomo.
I mean here we are talking about a part were few ohms difference can seriously affect your engine. It just doesnt make sense using a part that isnt going to meet the oem specs you are trying to get to.
Duralast is basically a knock-off brand and i've bought/gotten enough of their stuff before to be able to see the difference between it and nippon denso or sumitomo.
I mean here we are talking about a part were few ohms difference can seriously affect your engine. It just doesnt make sense using a part that isnt going to meet the oem specs you are trying to get to.
I do agree that oem is probably more reliable. If you can show me hard evidence that the difference is detrimental then sure I'll swap it out to the oem unit. Until then, let's not clutter this thread with an oem vs. aftermarket discussion. If you want to discuss more then please take it to pm.
07-07-09, 05:10 PM
#9
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nice write up. if people are wondering how the coolant temp sensor helps with mpg, id like to explain.
if the coolant temp sensor is stuck on either of the extremes (hot or cold) the computer will adjust fuel accordingly. lets say its stuck reading cold, it will cause the computer to dump fuel into the motor helping it to heat up, killing your mileage. and if its stuck reading hot, vice versa, itll pull fuel and retard timing.
if the coolant temp sensor is stuck on either of the extremes (hot or cold) the computer will adjust fuel accordingly. lets say its stuck reading cold, it will cause the computer to dump fuel into the motor helping it to heat up, killing your mileage. and if its stuck reading hot, vice versa, itll pull fuel and retard timing.
07-07-09, 05:15 PM
#10
nice write up. if people are wondering how the coolant temp sensor helps with mpg, id like to explain.
if the coolant temp sensor is stuck on either of the extremes (hot or cold) the computer will adjust fuel accordingly. lets say its stuck reading cold, it will cause the computer to dump fuel into the motor helping it to heat up, killing your mileage. and if its stuck reading hot, vice versa, itll pull fuel and retard timing.
if the coolant temp sensor is stuck on either of the extremes (hot or cold) the computer will adjust fuel accordingly. lets say its stuck reading cold, it will cause the computer to dump fuel into the motor helping it to heat up, killing your mileage. and if its stuck reading hot, vice versa, itll pull fuel and retard timing.
This logic is what I was aiming for. My car seems to smell a bit rich even when at normal temperature maybe due to the sensor reading too cold.
07-08-09, 11:41 AM
#11
Again, you replaced the wrong sensor for that problem. The single wire sensor which is located right next to the double wire sensor. It is incorrectly shown in your diagram as the oil pressure sensor. The single wire sensor is used by the ecu.
07-08-09, 12:14 PM
#12
According to alldata part number 8942220010 is the green sensor that I changed and refers to the coolant temp sensor. Alldata states the purpose of the part number as I quoted on the first post, "The engine coolant temperature (ECT) sensor measures engine temperature by sensing water temperature. The ECM uses this information for determining the proper air/fuel mixture for all conditions."
Also, alldata specifies that the temperature sending unit (gauge) has part number 8342020020. When I enter this number on various oem toyota parts vendors, it comes up as a temperature sending unit as well.
As a result, this information gives evidence that alldata has not made a mistake.
In addition, the 1UZ-FE guys in the reference threads replaced their coolant temp sensor with the same part number so did they get it mixed up as well?
Am still curious and eager to find out.
