Last week I shut down my 2016 Prius and I got a warning that the battery in the key fob was low on voltage. It shows up on the display and don't remember exactly how it was worded. I was impressed that this has been take to the next level. In the old days they just quit working and you had to guess that the battery was low. By the way it uses the CR2032 battery and is easy to change, directions are in the owners manual.
