Maybe the sensor is bad. And, yes, in driver side mirror arm.

 

Describe way out of whack?

 

Well today it was -2 deg C and the sensor was reading + 15 deg C.
Lorbay.

 

If it's in the Sun, that will cause it to be off.

Mine sometimes reads 135 degrees during the Summer when it isn't a bit over 95

Drive it for 5 minutes and it will read back to normal. Maybe ten minutes

 

I lick my index finger & stick it out through the vent window for the most accurate results; this particular app has been a reliable one ever since I started driving, shooting, etc.

I reckon "way out of whack" would be the ATS displaying an obviously wrong ambient temperature.

 

My 2014 would rapidly increase and decrease +/- 20 to 30 degrees at random and for no apparent reason. I thought you were going to say your 2014 was behaving similarly.

In any event, if it does a software update will fix it.

 

On others that I've had, they used to flip out if they sat in a drenching rain for a while.