Hi,
Trying to change the original CAS (9217853) on the BMW X1 (E84 buildyear 2009) with an used one. The reason for this, after a period of intermittent "ignition won't turn on" problems the ignition wouldn't turn on permanently with error "aa0a CAS control unit fault"

I tried "CAS replacement" in the following way:
🅰 original-CAS mounted
🅱 selected [CODING/PROGRAMMING] / [CAS Replacement]
[c] clicked [>] (next)
[d] Autohex get busy for a few seconds and says "Switch Ignition ON"
[e] turned ignition on and click "OK"
[f] Autohex get busy for a few more seconds and gives me back the [CAS Replacement] begin-screen as seen in step 🅱.

Next I tried to [Read CAS ISN] it then says: please do "CAS Firmware". So I did a CAS firmware downgrade which succeed succesfully. After that I read the CAS ISN and saved it in a file. I repeated step 🅰, 🅱, [c] with the original-CAS with downgraded firmware. It then says "Cannot proceed all steps" and gives me back the [CAS Replacement] begin-screen as seen in step 🅱.

So I connected the donor-CAS to the CAR and tried the following:
[g] selected [CODING/PROGRAMMING] / [CAS Replacement] and then [Advanced]. In the VIN field I replaced the donor-VIN with the original-VIN of the car, pressed "OK", but it then says "No working key in the ignition slot, please switch the ignition ON then try again" . However there is a key in de ignition slot, but the car doesn't recognize it as a valid key, thus failing in "ignition on". After selecting "OK" this attempt can not be completed and the function fails.
[h] selected CAS DME ISN Manager] and then [2. Read/Write CAS ISN]. After selecting "2" it directly says "No working key in the ignition slot, please switch the ignition ON then try again" (<- again there is a key in the ignition but due to not being recognized as a valid key, it is impossible to turn ignition on). When I press "OK" it says "Please do CAS Firmware and try again". So I did a CAS firmware downgrade on the donor-CAS. From there I again tried to [2. Read/Write CAS ISN] but this fails again, despite the downgrade of the CAS firmware on the donor-CAS, on the "No working key in the ignition slot, please switch the ignition ON then try again", Please do CAS Firmware and try again".
[i] Select [CODING/PROGRAMMING] / [Indiv Coding] and tried to code the donor-CAS with downgrade firmware. This fails with the message "Failed to encode Module, error ref: 8111"
[j] Select [CODING/PROGRAMMING] / [Indiv Programming] and tried to program the donor-CAS. It says "This CAS cannot be updated because of CAS firmware". So I restored the firmware to Original Flash via [CODING/PROGRAMMING] / [CAS Firmware] and selecting "Restore". After that I did repeated the programming of the donor-CAS which succeeded (however still no joy on the donor-VIN in the donor-CAS).
[k] with the "restore to original firmware" on the donor-CAS, I selected [CODING/PROGRAMMING] / [CAS Replacement] and then [Advanced]. In the VIN field I replaced the donor-VIN with the original-VIN of the car, pressed "OK", but it then says "No working key in the ignition slot, please switch the ignition ON then try again". Again; there is a key in de ignition slot, but the car doesn't recognize it as a valid key, thus failing in "ignition on". After selecting "OK" this attempt can not be completed and the function fails.

Next to that I tried pretty much of the above via the main menu "On Bench" while connecting both CAS's on the bench via the special Autohex cable (no OBD) and powering the Autohex with 12V externally. I succeeded in connecting with both CAS's after some attempts. Unfortunately I get the same problems as stated above; as in "switch ignition on" while I was expecting that while working within "On Bench"-mode this "switch ignition on" was somehow not necessary.

Remark 1; in all the above steps I did repeatably did a hard battery reset to make things work when I thought this was necessary e.g. when I got the message "Error in Communication with Module"
Remark 2; after restoring the original firmware back to the original-CAS (CODING/PROGRAMMING] / [CAS Firmware] and selecting "Restore") the error "aa0a CAS control unit fault" dissappeared. Not sure for how long. Is this a software/firmware problem which "healed" when downgrading the firmware of the CAS and restoring it back again? Any insights on this are welcome.

My question; given all the attempts described above, can anybody suggest a way to change the original-CAS with the donor-CAS?

The normal steps for the replacement of CAS (when original CAS is dead)
1. Get a working CAS with valid key
2. Read DME ISN and write it to CAS
3. Restore FA from LM to CAS from FA manager
4. Change VIN for CAS from advanced option in CAS replacement
5. GO back to the main menu in software
6. Start again with coding/programing
7. DO coding for CAS


Additional to this you need to restore cas at the end if you do cas firmware and also you can save key data from original cas from key learning option 1 and can add that to new cas.

Thank you for your reply. Regarding the working key; if there is no working key available, is it possible to create a working key from a blank key via the option "all keys lost" where the donor-CAS is mounted to the car? Or does this lead to adaption of other components (like the ISN/SK of the original DME)?

when it asks for isn for donor cas with no key give it as 8 zeroes,it may work.

just clone it with programmer,
15 mins job max

with AH if donor CASs mileage is better u cant reset it anyway, and it takes way longer including firmware downgrade and etc.

cloning is safer, cleaner

Thank you for your reply Levanime,

I searched for cloning specific CAS and saw alot usage with the xhorse vvdi prog. What programmer do you use for cloning CAS's? Any suggestions? We have a standard eeprom reader which we mainly use to edit/clone 8 pin eeproms. This unit is not capable of cloning CAS memory so we have to buy another one.

Thank you for your reply Levanime,

I searched for cloning specific CAS and saw alot usage with the xhorse vvdi prog. What programmer do you use for cloning CAS's? Any suggestions? We have a standard eeprom reader which we mainly use to edit/clone 8 pin eeproms. This unit is not capable of cloning CAS memory so we have to buy another one.

I'm using vvdiprog, so far no complains, doing cas3, cas4 without problem.

usualy I do like this:
-mount donor cas 2 or 3 and copy FA from frm to cas
-go to programing and update cas (autohex calculate proper flash to its car)
-than mount old cas and begin the proces of replacing cas
-transfer keys,vin,isn..etc from old to new
-yob done!car starts

If you find out yourself in problem and this not pass dont lose your time and yust read/write eeprom + flash by any programer(xprog,upa,vvdi..etc)
than finish it by update encode with autohex

Thank you for your reply Levanime,

I searched for cloning specific CAS and saw alot usage with the xhorse vvdi prog. What programmer do you use for cloning CAS's? Any suggestions? We have a standard eeprom reader which we mainly use to edit/clone 8 pin eeproms. This unit is not capable of cloning CAS memory so we have to buy another one.

vvdi prog is what I use,

although, r270 and xprog can do them as well.

but vvdi prog is best for now (for me)