I have made a duplicate of my car key ( 2001 E320) and I want to know if the key (reprogrammed used key) is original; manufactured legitimately by Mercedes or an authorized manufacturer. I didn't order one directly from the company, because it will take time to receive it.

And I want to know if this is legal and if the company sells new programmable keys.


2 Answers 2


Since the Marecedes "Smart Keys" are proprietary, only Mercedes's manufactoring partners make them; since they're programmed with electronic codes only Mercedes makes them and they're very protective over who they'll give a key to, since a blank key will program itself to any compatible Mercedes and become the key for that car.

This is why I really wouldn't recommend ever getting a key except from the dealer (and I'd want it in writing that if your key doesn't work you get a refund).

The key should look like one of the following models depending on year:

enter image description here

There's a newer model I'll try and get a picture of too. Which model it is doesn't matter as long as the internal bits work. You'll need the metal blade "emergency key" too, which is just a standard laser cut key, but it needs to fit into the fob so you need the right part number; if you have the wrong emergency key it won't fit into the fob and without fitting them together you can't put the fob on a keychain.

I'd be leery of this deal, but if they do in fact have one of the above key fobs, unprogrammed, the only thing that matters is that it works in your car. If there are "fake" keys out there, they won't work.

  • Getting the "emergency key" right really is important so make sure it fits before you leave the dealer; I've got a $170 key fob sitting in a drawer because they got the wrong part and I'm waiting for them to ship the right one.
    – Ben Brocka
    Jun 4, 2012 at 15:51
  • well, these keys can be reprogrammed.I have a chrome key (the fourth one) I couldn't get one from a dealer, so I reprogrammed a used key. You can get the data of the key chip from the chip of key slot in the car. I have overwritten the old data of the key EPROM with the data I got from the key slot processor and it worked. I can start the engine and lock the car with it. At first I thought that the key I bought was not original but after comparing it with the old one I found them identical. Thanks for your information Ben.
    – Alex
    Jun 4, 2012 at 16:40
  • @Alex really? Which key was it? Are you sure it was used? They shouldn't be able to be erased
    – Ben Brocka
    Jun 4, 2012 at 16:43
  • all these keys can be reprogrammed , I have programmed a chrome key ( the fourth one in the picture). you need an EPROM programmer to erase the data of the key. You can generate a new data for the key from the EIS of the car and then write it on the key. There are special softwares to generate key data from the EIS (some are online generators). here is a picture of the eprom to be programmed: freeimagehosting.net/mf6b3
    – Alex
    Jun 4, 2012 at 17:14
  • if you want more information about these tools you may check this site: noimmo.lt . And this is a manual of an online data generator: noimmo.lt/content/images/product/…
    – Alex
    Jun 4, 2012 at 17:19

If it's a chipped key, the duplicate is probably not going to start the car, but it should open any mechanical locks the original did.

I don't know any way to tell a duplicate key from an original, chipped or not, unless the duplicate is obviously cut from a generic blank. If you got a new key from a dealer, it will possibly be identical. I suppose though, for an 11 year old vehicle such as yours, the replacement part might be a generic part and might be different from the one you have.

I don't see why making a copy of a key to a vehicle you legally own would be illegal, but I'm in the US and I'm not a lawyer.

You can possibly get a replacement key from a source other than the vehicle manufacturer, but if it's a chipped key, it's possible it will have to be associated with your vehicle. The association process, if necessary, could require hardware an independent shop might not have, you might end up at a dealer. If no association process is necessary, the key (if chipped) will probably still need to be ordered for your VIN.

  • The keys use the same unlocking mechanism but the new styles of keys are different (and much nicer). If you buy a new key you'll get the new style. Mercedes keys don't need any hardware to be accociated, you just plug it into your car. However I've heard you're SOL if it's a used key, as they can only be programmed once.
    – Ben Brocka
    Jun 3, 2012 at 16:10
  • @mark: the key is chipped. I bought a used key and reprogrammed the chip to associate it with my car. It functions normally. I wanted to know if it's legal because I bought the key from a junk yard, not from a dealer.Mercedes does not sell programmable keys that I can program (I couldn't find any in my region).
    – Alex
    Jun 4, 2012 at 15:26

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