Huey52

... is apparently 3 years. I first-time noticed a Fob low battery dashboard indication when coming home from the dealership yesterday (hmmmm... why didn't they?).

So when I got home I tried my never used spare Fob and it was even dead-er. Fortunately a common CR-2032 3V wafer/camera battery.

21tesla

Yeah, I have replaced my batteries for my 2016 TT already, too

Gbob

Yup, me three.
The key fob has a lot to do and it seems to go through batteries more rapidly than before. I think it is the proximity door unlocking, as well as other features.

Nebuul

The other day, my fob became very unresponsive. I had a hard time opening my door from both proximity and button presses. I never saw a dash indicator, though.

​​​​Regardless, replacing the battery resolved the issue immediately. I'm glad they're cheap! This is after about 5 months of ownership.