[BMWbiker]

Car is my '15 328i xDrive wagon.

Yesterday was cold. Overnight Thursday night, the temperature was below zero degrees F. By noon, the weather was maybe 10 degrees F and sunny.

At about noon, I moved my car, without incident.

About half an hour later, I went to open the driver door. Nothing—it didn't unlock, no courtesy lights, no click. I tried to open the passenger door. Nothing.

For the first time, I used the emergency key to unlock the door.

The car said to put the key fob near the ignition. The car started.

It has worked without incident several times since then.

I replaced the key fob battery in November. The fob itself was in the house, so it was at room temperature, probably about 70 degrees F.

Any ideas what caused this?

[Elvet]

I have noticed something similar but unfortunately not with my BMW. In each case the vehicle's battery was too low to allow the door to open or car to start. This happened with a Mercedes Benz and a Toyota Prius. The Prius was more complicated as if any of three batteries was experiencing a low enough charge the key would be inoperable. Sudden cold can shock an otherwise working system by having a rapid drop in charge. Also, note, new batteries are new when manufactured and start loosing their charge immediately, so even if you recently replaced a given battery, if it was sitting around too long it may be more reactive to changing weather.

[WDE82]

Car's battery is due anyway.