[willisodhiambo]

Procedure "all keys are lost/do not work"
1. Unlock BDC/FEM
2. Read ISN DME
3. Invent any random cricto key (8 bytes, for example - 11 22 33 44 55 66 77 88)
4. Using this crypto key and the ISN DME that you read in step 2, calculate the new ISN FEM/BDC (I can help with this)
5. Write in FEM/BDC a new ISN, crypto key and ISN DME (all in DEcrypted format)
6. Make new keys using ISN DME

If your tool allows you to unlock FEM/BDC and DEcrypt data in it (with ISN DME)
1. Read ISN DME
2. Unlock FEM/BDC and get DEcrypted data (Crypto key, ISN FEM/BDC) using ISN DME
3. Make new keys using decrypted data

I hope everything is clear now)

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You can never make it work like that SIR.

So, makes the option of unlocking without working key pretty useless then?

Although it worked with an 868 key?

How many cars have been successfully made with 868? Without keys.

Just one car so far using this method. To solve my latest problem I managed to source another Fem with matching 434 key. I have several spare Fems now without keys, would be nice to know if there was a way to make these usable on 434 cars.

Well, Clone the current working FEM into any of the the donor FEMS then make a new key for the donor with the working key. That way you one working 434 FEM that you can use in future to relplace