Hi Paul,
I had a similar issue with temperature reported from my focuser (a TCF-S). I don't remember the value reported, but when the ambient temperature sensor attached to the focuser went bad, it reported a screwy number that was clearly not the real temperature. I bought a new probe from Optec, but it turned out that it was only the connection to the focuser that had become loose enough to cause the problem. You might check that connection.
Coincidentally I think, -274 is a few tenths of a degree C below absolute zero.