Another good thought. The Adafruit library still provides the error through readError(). That part was unaffected by my commenting out. In my case it's of little relevance, because any value below 100ºC is not a valid engine temperature (while it's running). Yeah, both probe types seem to break occasionally. Or worse, go out of calibration with the tendency to read low.
I'm curious how the Arduino based data collection performs out in the field. It's my first attempt.
Thanks,
Holger