# FOB Smart key vs. Duplicate key



## bmw2qnj2le (Jan 7, 2012)

Part 1: Electronic - Does a transponder smart key from one BMW model (3, 5 series) work in another BMW model (2000 740i)? Hint: I bought an used FOB key and reprogrammed it. It can open/lock door/trunk after reprogram. 

Part 2: Hardware - My duplicate key without a transponder can open the door, the trunk and it fits nicely in the ignition. I can smoothly turn the ignition to the start position and all the electrical in dashboard and radio work but the 740i does not start. Does it require the transponder to start my 740i? How can the BMW valet parking key start the BMW? Hint: Local locksmith makes the duplicate key.

Thanks in advance for your help.:dunno:


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## EconoBox (Aug 9, 2011)

How did you reprogram it?


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## Zeichen311 (Mar 31, 2011)

bmw2qnj2le said:


> Part 1: Electronic - Does a transponder smart key from one BMW model (3, 5 series) work in another BMW model (2000 740i)? Hint: I bought an used FOB key and reprogrammed it. It can open/lock door/trunk after reprogram.
> 
> Part 2: Hardware - My duplicate key without a transponder can open the door, the trunk and it fits nicely in the ignition. I can smoothly turn the ignition to the start position and all the electrical in dashboard and radio work but the 740i does not start. Does it require the transponder to start my 740i? *How can the BMW valet parking key start the BMW?*


First, it's called a "key fob" not a "FOB key," it's not an acronym. Second, the valet keys have transponder chips in them, just like primary keys. No chip, no start, so your duplicate is rather pointless.

Sent from my Kindle Fire using Bimmer


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## bmw2qnj2le (Jan 7, 2012)

Is the BMW dealer the best way to get keys for my BMW? or Locksmith can provide key fob and valet key for my BMW? thanks in advance.


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## Zeichen311 (Mar 31, 2011)

Yes, you need to order replacement keys from a dealership. They will require proof of ownership (typically the registration and matching photo ID such as a driver's license) and the VIN. I'm rather taken aback you found a locksmith clueless (or ruthless) enough to take your money and cut a key for you--BMWs have had "smart" keys and electronic immobilizers as a primary anti-theft measure for a dozen years or more. AFAIK the only way to obtain a replacement key with the proper RFID chip is from BMW. They are not terribly expensive for older cars like your 740i.

By the way, the RFID chip I'm talking about is not the same as the remote-control transmitter on the master key head/fob. The master, valet and wallet/emergency keys all have a tiny embedded transponder chip that the car interrogates to determine whether it's OK to start the engine.


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## bmw2qnj2le (Jan 7, 2012)

Thank you very much for your answer. Now, I understand how the BMW smart key fob works. Sometime the key does not turn the lock to position 1, 2. Is it the worn key or the ignition cylinder is getting old or the combination of the 2? Thanks in advance.


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## bmw2qnj2le (Jan 7, 2012)

to EconoBox. I went thru steps posted on the web and the remote is reprogrammed. It can open and lock doors and trunk. Now, I need to have a key with a chip to start the car in the ignition. I will go to the BMW dealer to order one.Thanks.


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