BMW FEM BDC Unlocking for Replacement and Programming Keys

BMW FEM and BDC in F series
BMW FEM and BDC in F series

BMW FEM (FRONT ELECTRONIC MODULE) and BMW BDC (BODY DOMAIN CONTROLLER) are the supersedes of CAS units. It is integrated with the functions of CAS, FRM, JBE, and ZGW. Comparing with FEM BDC also does the functions of REM which is a separate ECU for controlling rear electronic functions of FEM model cars. FEM and BDC are used in F series and G series BMW and have higher security and enhanced functions than the CAS models.

Immobilizer data is stored in BMW FEM/BDC and needs to be matched with DME and EGS for the proper running of the car. The central gateway module (ZGM) is installed in the Front Electronic Module/Body Domain Controller (FEM/BDC) as an independent control unit which is the gateway of Flex Ray communication on the car. Also, ZGM has FA stored in the latest BMWs.

Autohex II FEM Unlock Main Function
Autohex II FEM Unlock Main Function

All packages of Autohex II support the FEM/BDC unlocking. However, they have different abilties. Check Autohex II Packages

You can get more information about Autohex II from Autohex II Product page.

Fix corrupted or damaged FEM/BDC

FEM/BDC is the latest controller for BMWs so it is the most sophisticated in technology and security. Lots of FEM/BDC getting damaged or corrupted by improper coding or programming to make keys in the market. So AutoHex II has a far better solution for those FEM/BDC in case of corrupted or damaged data.


AutoHex II has a unique programming capability to program FEM/BDC Gateway and Body according to the FA in the GW (gateway). This ensures the proper programming and coding will be flashed to the GW and Body of the controller and return it back to normal. In some cases, if FEM/BDC EEPROM got damaged by some other tools when trying to program keys, AutoHex II can repair this corrupted in most of the cases to make it in normal mode by special steps carried out by our tech team.

Unlock FEM/BDC Security

As described above FEM/BDC is highly secured. For doing various jobs like key programming, changing VIN, and Editing stored ISN in FEM or BDC it is important to unlock its security. The unlock procedure for FEM/BDC can be done on the bench using AutoHex software. After the unlock it will generate a secret file at the end which can be used to do any function for FEM/BDC modifications.

After AutoHex II generates the BMW FEM/BDC Secret file, all the other jobs like FEM/BDC key programming, VIN modification, ISN change...etc. can be done by OBD and also on the bench, no more bench compulsory work as long as you have the secret file.

Three Methods to Unlock FEM/BDC

Unlocking BMW FEM/BDC with AutoHex II does not need any soldering or unsoldering on FEM/BDC. A clear schematic wiring is provided in the software for better user understanding. AutoHex II will start the procedure by collecting all important info from FEM/BDC to generate a backup file (a restore point) which is very useful when some problems happened because of power failure or something related.
AutoHex II is the safest and most secured tool that deals with FEM/BDC function as it will not start any modification before a backup file is generated.

Using original DME ISN of FEM/BDC:

In this method, FEM/BDC is unlocked using the original DME/DDE ISN of the module. This option can be used when programming all keys lost situations of the car. DME/DDE ISN can be read from the original DME/DDE of the car using AutoHex II in the Factory mode option without opening the engine controller. From unlock option using DME ISN it is possible to load the ISN file saved from factory mode before. Once proceeded it will take 10-20 mins to unlock and generate the secret file.

Using working Key:

FEM Unlock with working key
FEM Unlock with working key

When there is a working key available and want to make extra keys, this option can be used to unlock FEM/BDC. A Key coil from any BMW F series is needed to read the working key in software. The wiring diagram shows the key coil connection with FEM/BDC. The key coil should be attached to FEM/BDC in this process and the key must be kept near the key coil. Key identification on FEM/BDC and software can be checked from the key learning option1 as the key showing yes in the slot. Once the key shows in the slot, FEM/BDC can be unlocked from the working key option to generate the secret file.

Without ISN and without a working key:

AutoHex II is the only tool that is able to work in this kind of situation. This option can be used when replacing FEM/BDC with a second-hand one, or when a car lost DME and all working keys. When you use this option to unlock FEM/BDC AutoHex II will reset FEM/BDC and generates a random ISN and its corresponding secret file. After getting the secret file, you can program a new key for this FEM/BDC, then you can either write the original ISN from DME/DDE to FEM/BDC or write the generated ISN for FEM in the DME/DDE.

FEM/BDC Mileage Reset

FEM BDC Mileage Reset
FEM BDC Mileage Reset

AutoHex II can reset the mileage of FEM/BDC to zero this will help when you replace FEM/BDC from one car to another. There are options on the bench unlock menu for mileage reset integrated with unlocking of FEM/BDC and also a separate option as mileage reset only like the below image shows.

For mileage modification before mounting FEM/BDC back to the car you have to modify mileage in KOMBI (this can be done by HexProg Tool) Once FEM/BDC is connected back to the car after reset, it will adapt mileage from kombi and store the KOMBI mileage in it.

FEM/BDC Cloning

FEM BDC Replacement
FEM BDC Replacement

Cloning the full data from one FEM/BDC to another is possible in Autohex II software. For doing this you need to unlock both original and donor FEM/BDC. All the data stored in control like keys, ISN, VIN, etc. will be transferred from the original to the donor. This option helps to replace FEM/BDC in the easiest way when the original FEM/BDC is damaged. The procedure is as follows:

FEM/BDC cloning if you have a key for the original fem and used one without key

  1. Unlock the original FEM/BDC with working key
  2. Unlock and reset mileage on used FEM/BDC with option3
  3. Connect original and save FA from original
  4. Go to CAS replacement and proceed
  5. With the original FEM/BDC software will ask to load its secret file, load that original FEM/BDC secret file
  6. Software will then ask to connect donor FEM/BDC and load its secret file then load the donor used FEM/BDC secret file and process complete
  7. After cloning is completed, load original FA to donor FEM/BDC
  8. Go out of coding/programming and come inside again and program donor FEM/BDC GW and BODY
  9. FEM/BDC Cloning Completed
FEM BDC Cloning Completed
FEM BDC Cloning Completed

FEM/BDC Replacement with Dead Original

Another astonishing feature comes with AutoHex II when there is no original FEM/BDC available or no communication with the original module. AutoHex II has a dedicated procedure to solve this situation with only donor FEM/BDC.

Replacing FEM/BDC with used when no communication with the original

  1. Unlock and reset mileage for used FEM/BDC in AutoHex II
    • If got a working key for donor FEM/BDC, unlock using that working key 
    • Use option 3 which will unlock without ISN and key
  2. Read ISN from the original DME
  3. Write DME ISN to FEM/BDC from ISN manager option 4
  4. Change VIN for FEM/BDC (Cas replacement-->Advanced)
  5. Program key if needed from key learning option2
  6. Connect FEM/BDC to the car 
  7. Restore FA from the FA manager
  8. Go out to the main menu and come inside the coding/programming
  9. Program GW and BODY from Indiv programming (note it will do only coding if fem already updated)
  10. FEM/BDC Cloning Finished
FEM BDC ISN by Autohex II
FEM BDC ISN by Autohex II

Replacing FEM/BDC With a Donor Has a Working Key

Another situation is donor FEM/BDC got working keys and if the original FEM/BDC is cloned to the donor the keys in the donor fem will be lost. In this case, we can use a different procedure to keep the keys in the donor fem intact.

Replacing FEM/BDC when donor FEM/BDC have working keys and have communications with original FEM/BDC

  1. Unlock the original FEM/BDC using the working key in AutoHex II
  2. Read and save ISN from the original FEM/BDC using the secret file you got after unlocking from ISN Manager option 4
  3. Save FA from FA manager from the original FEM/BDC
  4. Connect used FEM/BDC to the AutoHex II
  5. Unlock and reset mileage for used FEM/BDC using the working key option.
  6. After getting the secret file for the used FEM/BDC go to ISN manager option 4 and write the ISN saved from the original FEM/BDC using the used FEM/BDC secret file
  7. Change VIN for used FEM/BDC from CAS replacement-->Advanced
  8. Program key if needed using secret file for used FEM/BDC
  9. Load already saved original FA to used FEM/BDC from Fa manager options in AutoHex II
  10. Go out of coding/programming and come inside and Program GW and Body from Indiv Programming for used FEM/BDC
  11. Finish

In other cases, apart from cloning and replacement of FEM/BDC. Using secret files from unlocked FEM/BDC, it is possible to change VIN and ISN to match with DME/DDE or car.


Unlike all other tools that support FEM/BDC, AutoHex II does not require to solder or unsolder any component from the FEM or BDC, it is required to connect 8 pins eeprom clip to FEM/BDC connector only.

Check for more information about Autohex II.

Last Update: 6/1/2022
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