Batteries in the sensors. Not lifetime and they can go bad before you get out of warranty. Cost about $125 per wheel to replace. My 2010 model has had all four go bad. Cheap Chinese batteries is my guess.
“Batteries in the sensors. Not lifetime and they can go bad before you get out of warranty.”
There are other things on a vehicle that are also not covered by warranty. Filters, and bulbs and breaks etc. Having them not covered should not be a problem.
You can replace the batteries yourself, I’ve done it.
Look on YouTube for videos.
http://www.youtube.com/watch?v=QjrT7WBG6U8