Coolant temp sensor testing needs to be done at all different temps?
 

Or can I assume the ECU coolant thermo sensor is OK if it's within specs at the current temp?

92 22RE

Thanks.

I personally have had a HONDA coolant temp sensor fail and make the system think it was incredibly cold out, but the reading was still within the realm of possibility. So i'd take a couple readings at least, one cold and one at the temp you think you are experiencing the problem at.

The coolant temps sensor is not a switch, it's a thermistor. (But you knew that, because you were testing resistance.) http://web.archive.org/web/201311071...40engineco.pdf I don't "know" if you can make that assumption, but that's the one I would make. The failure modes that I can think of would all pull the measurement out of spec at room temperature, and pretty much any other temperature.

But if the sensor is out, my curiosity alone would make me dip into some boiling water.

Yep, measure resistance while dipped in boiling water and then while dipped in crushed ice.