Originally Posted by opensourceguy
That would mean i'd have to take out the sensor right? If I can get one for >$10, I may as well go for it, not like it'd be the first thing on the car to break.
Or leave the sensor installed, check resistance directly at sensor with connector removed. With engine stone cold (equal to ambient outside temp) check resistance of ect and compare to service manual. For example suppose ambient temp is 80 degrees, resistance should be 140 ohms, and you read 139.3 ohms, then the ect is good. Those values I call out are just arbitrary, you'll have to refer to service manuals for exact figures. You could also warm engine up to operating temp (assuming it is close to 200 degrees) then check resistance also as a comparative reading.