A friend of mine purchased a new vehicle. Unlike vehicles in the past, this vehicle does not require you to insert a key to open the doors or run the car. The key merely must be within a couple feet of the car and the doors unlock and the engine can be started by pushing a button without needing the key physically.

This presents and obvious security problem. For example, getting something out of the trunk. Since my friend would be close to the vehicle, the doors are unlocked and someone could simply enter the unlocked vehicle and start the car.

According to my friend, this remote works off of some sort of radio wave mechanisms. My friend thinks the best way to resolve this problem would be to purchase a case for the “key”/remote so that, as long as the case is on it, no signal can be sent to the car and thus problem avoided.

Are there any good known solutions to this problem? If putting a case on the key is the best solution, what are the ideal characteristic in such a case? I don't really know what my friend needs.

  • 1
    Which vehicle is this?
    – Zaid
    Aug 25, 2015 at 4:32
  • Reason #981 not to buy a car with keyless ignition. These things are going to cost you big time if it breaks.
    – rana
    Aug 25, 2015 at 18:51

2 Answers 2


If the key doesn't have a battery you can remove, it might be powered by RFID. Try wrapping it in aluminium foil.

  • +1 My friend tried it and that worked! That is so cool! But my friend needs something more practical. He can't wrap the remote in aluminum foil each time he gets out of the car. Does this mean we should look for a case lined with aluminum? The remote is roughly (he measured it) 1.4cm (.55in) depth by 6.35cm (2.5in) length by 3.5cm (1.38in) width. Is this like buying an iPod case where it will be common and easy to find or will we have a tough time finding something like that? In other words, we want a case for it that does exactly what the aluminum foil did. Aug 25, 2015 at 5:55
  • 1
    Any metal case should work, but you can also line the inside of any case with foil. I didn't know key cases were a thing, so I don't know how easy it'll be to find. Maybe a hide-a-key or altoids tin will do the trick. You might want to line the inside with fabric so it doesn't rattle.
    – ki9
    Aug 25, 2015 at 6:32

The smart key system you are referring to is specifically designed to work at very short distances requiring the key to be inside the car before it would start. When i worked at Mazda on cars with smart keys, the car had 4 antennas just to make the system work seamlessly with the short range in mind. There was an antenna in each front door and the trunk to allow the door and trunk to be unlocked and there was an antenna in the dashboard that authenticated the remote to start the car. Further if the key was being detected by the trunk antenna car starting would be disabled even if using a second valid key for the car. I have major doubts that if the key was located behind the car someone could get in and start it.

  • This proved to be true as well. Sep 1, 2015 at 6:20

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