Ambient Air Temp causes several problems...
On my 2018, in the last several days, with the true temp being from 25-35 degrees F, the outside temp gauge would work for a while, then, erratically, it would drop to -30 or or lower, then just go up and down constantly between 0 and -30 degrees F and then, sometimes up to normal, an even a couple of times, all the way to 70-80 degrees F, before falling to around -30 again.
Then, there are times it will blank out altogether. When the temp blanks out or the reading is below about -20 degrees F, the Auto-Start/Stop warning light comes on and the Service Engine Soon light is set. The next time I start it, the Auto Start/Stop light will be out, but the SES light remains on. If the temp reading drops low again, the Auto- Start/Stop light will come on again.
But wait, there's more- Here's the last crazy tidbit- when the outside temp is going up and down under 0 degrees, the inside heat barely heats, certainly not up to what it is set. However, as soon as the temp approaches the true temp OR (and this is crazy) the temp reading goes out altogether, the heater kicks into normal mode and brings the interior heat up to what it is set at.
I'm guessing a bad sensor (no duh), but as always, these things can also be a wiring issue. I will let you know.