Can Someone Steal Your Car With Another Remote?

Most newer vehicles now come with key less remotes that at a click of a button open up your vehicle. So I found it interesting over the weekend when someone asked whether another remote could open their car? You see, once you have been labeled as a geek, you are supposed to be an expert in everything electronic. Over the years I have fixed items since as paper shredders, radio’s, electronic watches and other items that have been shoved in front of me.

So when I was confronted with a question concerning remote key less entry into a car, I must admit I didn’t know the answer. Sure, I suspected that the code must be encrypted and that the signal had to change at each use, but that was just a guess on my part. So I did some investigating and here is what I found.

The key code for your remote keyfob is stored in the vehicle itself. Each time the keyfob is pressed and different code is provided which prevents other remotes from opening your vehicle. As I suspected this information is encrypted. So in a nutshell, it would be highly unlikely for another remote to open your car.

But here is something else I also learned. Those commercials where the driver just pushed a start button with no key, also is interesting. This system works by using a smart card which the driver keeps on their person or in a purse. With the proper smart card the car starts when the button is pushed.

Comments welcome.


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I have been writing for Lockergnome for eight years.

  • Brian

    So does that make it impossible to beat the encryption?


    I often wonder the same thing about garage door openers…..Could you check on that?

  • Billy Doyle

    The smart card bit is clever. I always wondered why you intentionally make your car easier to steal, but that’s really cool!

  • Ron Schenone

    Nothing is impossible.

    Bugsy handles garage doors.

    Billy Doyle,
    I thought it was cool as well.

  • Mr. Bond

    In response to your question, when garage door openers first came out, as when most things that come out, the manufactures would use radio waves or ir signals to open and close the doors. The signal was set in the remote itself at the manufactures facility before it was sent out.

    What some people didn’t know what that by tearing apart the remote you can change the ir signal by a series of mini switches. All one had to do was to drive around your local neighborhood and mess with the switches until the garage door opened.

    Now this was manufature specific so you couldn’t open a door to all manufactures.

  • Davis

    I was wandering the same thing about the car remote unlock thing. I just recently bought a used truck with keyless entry. The dealer showed me how to “program” the remotes. Its actually amazingly simple. All you need is a remote and less than a minute in the car with the keys.

  • None Required

    When your car is built, the key fobs are mated to the module in the vehicle. Even though the code rolls, the fob itself is mated to the vehicle. So, while it may be possible to find another fob that has the same exact ID as yours, the odds of it happening are astronomical. In the newest systems, you need one of the original fobs to even program another replacement fob….

  • Michael Primiani

    Ive done that in a parking lot with an automatic car starter!

  • Don Naphen

    I recently had a remote start installed in my ’04 Jeep Grand Cherokee. The key itself has a chip that mates with the computer in the vehicle. When the system was installed, they had to program a blank key (without cutting a key) and it became part of the system. The way it was explained to me, even if one was to obtain a key that fit the ignition switch, without the programmed chip, it would be impossible to start.

    I guess anything is possible with regards to “hot wiring” the thing, but far more difficult than the good old days. Fords were the easiest to steal … just run a jumper from the battery to the hot side of the ignition coil, then, using a screwdriver, cross the 2 terminals on the solenoid switch which was mounted on the fenderwell! Yeah, security has definitely come a long way Ron.

  • Ron Schenone

    Thanks for the comments everyone.

    Heh Don,
    Thanks for the info.

  • Michael Rivera (mrivera1)

    Yeah, car remotes are permanently mated to the vehicle in question. Usually an original remote is required to “donate” the rolling code signal to another one. Not only that, but even if the person gets in the car, they would need a key with the correct code for the immobilizer system. Hell, you can’t even jimmy a lock to unlock it in most modern cars, so opening it without causing physical damage is very unlikely.

  • Deb

    You ask can another remote could open their car? The answer is yes. How do I know? My mother got into a car and started it and then realized that it wasn’t her car – which was parked only a few spots away.

    What was even weirder, was that although both cars were in the Bronx, both cars had CT license plates.

  • Jeff

    I have in the recent past owned a Suzuki Estate and on two different occasions parked near to a Volvo and when the owner of the Volvo locked their car my car was unlocked. So it can happen.

  • Ron Schenone

    Thanks for sharing your experiences with us. Interesting how a remote can open another car.

    Regards, Ron


    Hey Ron…..I also wonder about that Bugsy guy…….

    And thanks for the info Mr Bond….James I assume….

  • Pizzor2000

    I’ve heard stories of people using devices to steal the signal from a remote when someone locks their car, and can then use the device to unlock the car and break in.
    I’m not sure if this is another urban legend, or if it’s just as feasible as intercepting Wi-Fi.

  • Louise

    Every night my car trunk would pop open so we had to remove the automatic trunk opener. I asked my immediate neighbours to try their remotes and it wasn’t any of them.
    Twice I remember my neighbour’s garage door opened when they were away. They claimed it was low flying airplanes. My son’s new remote car starter started his neighbours car.
    Don’t trust any of them to be secure.

  • GadgetNut

    I have read accounts of the weak encryption on the electronic keys for the high-end BMWs being broken as well. Turns out that the encryption is less than sixty-four bit, but BMW doesn’t see it as a problem….

  • Ron Schenone

    Thanks for the information everyone.
    It is appreciated.
    Regards, Ron

  • roxy

    So i recently lost the intelligent remote and i bought one online but is it possible that maybe i can program the new remote to my car???

  • Dan

    Well today my father, who owns a Mercedes C350, came out of a store, unlocked what he thought was his car…It beeped, the trunk poped open and everything with the key, little did he know as soon as he got into the car, it wasnt his. He noticed an Infinity emblem on the seat and was shocked to find out it wasnt his car.

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