The motion sensor trigger on a IR sensor detecting a heat change in a certain time frame from a moving object through the detection field. So I guess that a cold temp with a cars heat passing the sensor may trigger it.
I have seen warranty breaking mods that change the detection curve to reduse false triggers.
...I do have that MS16A positioned to try and not get too much of the street, but in order to make sure I cover all my property, they do get triggered by vehicles now and then...
...a LOT of false triggers by the MS16A's. I don't know if it's from the heat of vehicles being a greater contrast or just from being cold; but since I don't get many falses from my backyard, I'm leaning towards the vehicles...
Thanks TTA for mentioning blocking!