My front parking sensors work great. But I've yet to hear a peep from the back sensors. They are silent - not working at all. I've set what I can find to set - so what am I missing?

 

Have you determined that they actually don't work? Have someone walk close to the rear sensors and see if they activate, and back up to a brick wall and see if the rear sensor doesn't go off. The rear sensor can be adjusted for far away or closer activiation.

 

It's hard to say without having your car to try ourselves. But if they're not working then you need to have the Lexus mechs have a look and correct. In the meantime be diligent with your rear camera.

Let us know what the issue was after you have it looked at please. Good luck.