1998 Ls400 Ect Sensor Removal Engine Coolant Temperature

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Since I have the throttle body off, I decided to change out the ECT or Engine Coolant Temperature Sensor. This sensor is located on the left (passenger side) on the water inlet. If you are looking from the passenger fender, you will see it under the throttle body.

My car is a 1998 LS400 with 118,000 miles. The ECT has never been changed. I currently do not have any problems with the car as far as ECT related issues but decided to change it out since I'm already in there. The replacement costs anywhere from $12 to $20. If you pay more than this, you are getting ripped off and this includes the dealership. This sensor is very generic and imo, this is one part that really does not warrant buying OEM. And that's coming from someone who is a full believer in OEM.

If you are starting from scratch, the factory manual says to:

1. Remove the V-Bank Cover

2. Remove Battery Clamp cover, Air Cleaner Inlet and Intake Air Connector

3. Drain engine coolant

4. Remove throttle body (I'm not exactly sure if the TB actually needs to be removed. I'm sure the sensor could be removed without the TB being removed. But for me, with the TB out of the way, the job was a cinch and from here the job is very easy:

5. Unplug the black connector using a flat tip screwdriver and pull the connector off. Be careful. I had to pry with the screwdriver and push/pull the connector at the same time. The insulation covering the wires will be brittle and fall off.

6. Using a 19mm socket or wrench, remove the ECT sensor. You will notice that compared to a new sensor, the old one will be darkish green in color and may have slime and/or caked on deposits on it. The old sensor also uses a copper gasket. The new sensor will have the gasket included. For those who do not have a torque wrench, it took me 5 turns to remove the ECT. For those of you wanting to go the extra mile take some electrical tape and wrap the wiring to protect from the heat.

7. Torque the new sensor to 14 ft/lbs. Don't over tighten too much or you risk cracking the housing. I did this before many many years ago on an old Toyota Supra in high school before I knew anything about torque wrenches. Not a good feeling. :cries:

8. Connect the plug and you're done.

I can't say anything about the remarkable and improved throttle response and power that many claim. I changed an ECT on my old 1991 Toyota Camry recently (with 200K) and I did not notice any difference. I'm sure it doesn't hurt. Regardless, it's good to change out the part because it's a very cheap part and very easy to do. Don't forget to assemble everything back together. Now start the car and enjoy your new 15hp increase ;)







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This is a nice write up.

However I always wonder why people just replace sensors without confirming the resistance or the function which can be checked easily by a multimeter.

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