Unfortunately for everyone wanting to add a remote key to thier 02-04 Mini Cooper, BMW/Mini decided to use an extra layer of security in order for the remotes to function with the car. This involved a bar code that is coded into the body control module of the car. For those wishing to purchase a new key, this is no problem as long as you live within driving distance to a Mini dealer and don’t mind paying a lot for a new remote key. One way around the expense is to purchase a used remote key and transfer the transponder chip and cut blade from a non remote key to the used remote key. The problem up to now has been that unless you had the barcode from the used remote, you were out of luck in getting the remote programmed to the BCM. BMW/Mini are no help in getting the barcode for your remote, instead choosing to charge owners a premium for a new remote key. After a lot of research and work figuring out the cipher, I finally figured out how to decode the 6 digit code that is on the sticker within 02-04 remote keys. I could have easily kept this info to myself and/or used it to make money selling codes to Mini owners. Seeing as I was trying to save myself money by figuring all of this out, I decided it would be against what this stood for to me and have decided to release the decoding so anyone looking to do this themselves has access to it for free. I hope the many hours I spent on decoding and writing this guide is appreciated and that it is spread far and wide so everyone wanting it has access to it. Keep in mind that a used remote may be bad and non-working. It should also be noted that this worked for me and I verified that the procedure is good. Hopefully any remote you purchase is in working order and you have success with this procedure. All I can say from here is Good luck, and your welcome. The rest is on you.
It took several hundred hours to gather all of the info I needed to decode the cipher and figure out the coding procedure to get the remote working with the car. The piece of info I needed to break the code came when I found a BMW TIS named “Coding a new remote key”. Currently this can be seen at http://tis.spaghetticoder.org/s/view.pl?1/07/82/16 I have also copied the TIS into the guide on the following page in case the link dies in the future (I know I hate when that happens, Your welcome). Ignore the code used on the sample barcode, it is made up and does not follow the decoding exactly. It is only meant to be used here as a guide to understanding how the code works.
Again, before you purchase a used remote, make sure you understand that the transponder chip and blade will need to be replaced unless you just want remote functionality. The used transponder chip is NOT coded for your car, and the blade will NOT open or start your car. The remote is the only part of a used key that can be transferred unless you have a way to rewrite the transponder chip.