Thanks for the info Art. The thermocouple probe was not coupled with the device under test, and I checked the temp of the water before and after testing the sensor. By the way, there was only one device under test, it has two NTC thermistors in one housing. That is what the two numbers are for.

Because I only have the one meter, I just pulled the thermocouple out of the water, changed leads in the meter (the other end was already clamped to the sensor to save time) and lowered the sensor into the hot water. Pulled the sensor out and changed contact quickly to check the other thermistor. When done, I switched leads back to the thermocouple and re-checked the water temp at about the same location in the jar as where the sensor was sitting. In all cases, it did not change.

I used a full (of water) quart canning jar sitting a 3 quart sauce pan that was about 2/3 full of water. That was to protect the pan from getting any car crud in it. I guess that because of the relatively large mass of water involved, about 3 quarts, it stayed the same temp. during the actual testing of the sensor.

Thanks to you both, and I guess I'll just put it back in and hope for the best.
--
1955 Human, Scott; 1991 745 Turbo, Brunhilde; 1990 745GL, Snuggle Bunny