Mine locked up a couple of times. But, since mounting it in front of an air vent (with outside air selected), it hasn't frozen. I'm not ready to say that's the solution that worked for me, but the evidence is there so far. I had it mounted on a piece of trim just in front of the plastic cover on my gauge faces. However, during the lockups, I noticed a good bit of heat in that area compared to just outside of the steering wheel area. Hope that helps. It isn't in a case. Because of the lock ups, I have not been able to get a tankful of numbers for calibration, just yet. However, I'll be driving close to 1k miles this weekend, so it should be good to go within a week.
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"It is foolish and wrong to mourn the men who died. Rather we should thank God that such men lived."
- General George S. Patton, Jr