FOB Key is not detected

Don't assume that a new battery is a good battery.

 

It sure does sound like a dead fob battery.

FYI, you can always start your car, even with a fob with a dead battery, by holding the fob next to the Start button for a few seconds while pressing the brake. Then press Start.

 

This is a different issue than yours, I think, but if my cell phone is in my pocket with the fob, the cell phone will sometimes prevent the car from recognizing the fob, especially if the fob is under my iphone. That has stopped the door lock from opening but I don't recall it doing anything else.

 

If someone is in your car and they have a key fob from another Prius, your car might not start and will say no key detected or if your car is running it will say no key detected but your car will continue to run. This will not happen with all other prius's fobs but there is a chance it can!

My coffee buddy has a 2010 Prius and that is what happens to him every time I ride with him, I have a 2012 Prius, we always forget but the car always remembers. We put a little metal box in his car and I put my keys in that when I ride with him works great. I have checked out about 6 Prius's from coffee buddy's and alot of cars at our local dealer no problems with any body else's Prius's, camary's, ect. Go figure. I have heard about other people that said they have had this happen. I suppose it's more likely in a two car family to be noticed. Hope this helps!

 

Ditto here, My brother has a 2010 and I have a 2011 I had his hat in my car and i wanted to return it so I asked him for his keys and went to my car and with both fobs in my hand, my door wouldn't unlock after opening with push button on fob I also could not lock my car. I went to his car to put his hat in there the same happened with his car.
The dual signals must cancel out the receiver.

 

The signal frequency or codes must be close to each other. My wife carries both her Prius and my Camry's SKS fobs around in her purse with no problems whatsoever.

SCH-I535