"Thanks mP1 for the reply. As I said to Dave, I will just give up  on the ultrasonic sensors."

"Thanks much for the info Dave.I will have to give up on it too."

"Hi Dave, did you ever get your cold temperature failure fixed of the MaxBotix ultrasonic sensors?
I bought a few and had the same issue as you described on your landing issue.
I received an RMA from Maxbotix, but I noticed no difference after the…"