I finally resolved the problem. In an RV-12, in order to get to the end of the cable from the OAT probe it would be necessary to remove the seat custions, the seat backs, an inspection plate under the belly of the plane, drain the fuel tank, remove the ELT, remove the fuel tank, remove the baggage wall closure panel, put planks on the open bottom, then crawl into the tail to get at the plug from the OAT sensor, and try to make resistance while laying on your back in the rear of the plane.
I wanted to do ANYTHING but all that. I wondered if the D180 might be subject to something that we have all seen on laptops or desktop computers: When bringing them "up" sometimes something is corrupted and things don't work right. A restart generally cures things. So I looked at every setting that could be changed; changed it, and returned it to the original setting. It worked. The OAT read the correct outside temperature and was no longer 'stuck' at negative 46-degrees.
