Thread: Coolant Temperature Sensor

TEFLON it is suggested but not needed i have switch both of those last week didnt use teflon if u use teflon dont go over board .

You shouldn't need teflon tape. The sensor comes with a crush washer that seals the sensor in beautifully.

It's a tough fit as it is, and not really a whole lot of room to thread the sensors in or get wrenches on them, so I'd honestly recommend against teflon if this is in-car maintenance.

If it's on an engine stand, then it's entirely your call since you've got the space and good angles.

biggest mission in the world.. i swear i rather remove waterpump with motor still in it.

It is NOT suggested, in fact it say's NOT to use teflon tape in the service manual ,,,


pick up a service manual and read it sometimes instead of just talking.!


I found out the hard way when I did my JDM swap,,, I USED tape and my temp sensor and the motor had a hard time warming up and fans would not come on until nearly over heating.. I picked up the service manual and flipped through it and found that it say NO TAPE on temp sensor!


I simply removed the tape and have not had any issues with starting up or fans working properly. (very hard to do with motor in! but I have small hands)





I hope you figure out whats up,,, just trying to help ya,, anyway the tape was my problem and our symptoms are very close to the same.. I look inside my service manual every time I have an problem and it seems to be pretty much right on everything I throw at it ,,,

As of now, I have a brand new sensor in there, and I soldered high-temp silicone coated wiring to the connection spades and potted the whole deal to ensure that it's never going to be a connection issue

Although the fans still don't kick on, it seems to be running fine. Part of me suspects it's still rich, and my future tune-up will tell me. Right now, though, 0 deg temperatures are standing in my way.

I did find one thing that would speed this whole diagnosis up:

No cat and i know for a fact my sensor is unplugged, and shuts the fans off when plugged in. maybe theres more that one problem there? I'll tackle this one and see where that takes me.....

kiddie stuff sam, haha. Just wanted to add my 2 cents for those of you that have a hard time changing your cts on your highports. You can just cut or grind off the tab that is on the intake manifold that doesn't allow you to get a socket down on them...no ill effects. check my build I've got a pic somewhere in it.

Cat or no cat, you still have piping there.

Most likely situation: since you've been running the car with the cts unplugged , the ecu is not adjusting your fuel based on o2 sensor readings, and you are running very rich. This results in the excess fuel exploding in your exhaust.

Simply plugging the cts back in will not fix the issue. You need to clear the ECU codes.

So, plug the sensor back in, clear the ECU, and drive it for a bit. See if that code returns. If it doesn't, you could have another issue, or your cts might be giving bad readings that are still within the expected range (i.e. says it's 90deg when it's really 110deg).

Run it in open loop, lose the o2.

Is there any retuning that is needed to do this or is it as simple as unplugging the oxygen sensor?