Wow, just happened to me today in our new to use NC!
Happened to me on the very first day that I got mine home (about 4 1/2 years ago).
But there was no phone inside the car at the time.
The only thing I can put it down to, was that the car was parked a few feet away from my front window where our wifi router sits.
Apologies for resurrecting such an old thread but does turning the internal alarm resolve this issue on an NC 3.5 or is the definitive solution to turn off the Wi-Fi and Bluetooth ?
I will need to leave my phone locked in the car for a couple of hours and don’t want to upset the neighbourhood.
Try it out, lock car as normal but turn your data, wi-fi Bluetooth etc off on the phone first.
Or just turn the phone off🥴
My alarm sounded after around 5-10 minutes leaving the phone in there with the data/WiFi connected.