Reprogramming a key, previously erased

[Binary420]

I have a few questions regarding key fob programming. This applies to any immobilizer programmer that is cas3+ compatible, I own a LAUNCH x431 scan tool, as well as the x-PROG 3 key programmer module.

Once I have backed up the current .bin key file, containing the 10 key ids
If I were to then erase one of those keys using the scan tool,

Would it be possible to later re-add that same key info (just the 1 key that was erased) to a slot in a different, current key file
(either an unused slot, or the same slot it was already in prior to being erased)

in other words, once it has been erased from the car, is there any way to make that key work again?

[nycplumber]

I'm not sure I understand you question fully but I believe that to be correct. When I got a new key programmed he deleted one of my old keys (the missing key) and wrote over that one with the new one. He explained the reason for doing this is 1. security and 2. since ecu only allows "10 keys". But in reality it can be infinite because you can delete old keys. I see no reason why you can't program old key again

[Binary420]

Originally Posted by nycplumber

I'm not sure I understand you question fully but I believe that to be correct. When I got a new key programmed he deleted one of my old keys (the missing key) and wrote over that one with the new one. He explained the reason for doing this is 1. security and 2. since ecu only allows "10 keys". But in reality it can be infinite because you can delete old keys. I see no reason why you can't program old key again

Thanks for your reply.

So if a key that was erased from my car is later located, i can copy the key id / remote id of that key from any previously saved key.bin file, and paste it into my current key file, in any of the 10 slots which are unused?

Cause thats what I did, and the key works(starts engine), but the remote unlock/lock does not work, and when i attempt to perform dme cas sync operation, it fails to complete

[SilverSlug]

When you say that it starts the engine…

Do you mean by inserting it into the ignition slot OR are you able to keyless start the engine while the key is still in your pocket?

If you have Comfort Access, you can replace the battery in the key, and at least eliminate that as the culprit.

[Binary420]

Originally Posted by SilverSlug

When you say that it starts the engine…

Do you mean by inserting it into the ignition slot OR are you able to keyless start the engine while the key is still in your pocket?

If you have Comfort Access, you can replace the battery in the key, and at least eliminate that as the culprit.

Yes i meant by inserting the key into the car slot and pressing start.
I do have comfort access but i have yet to get comfort access working with any of these chinese key fobs.

[SilverSlug]

Ah okay, all of your fobs are Chinese style replicas?

Only Comfort Access fobs have removable batteries, the non-Comfort Access fobs do not.

So, if your Chinese fobs don't have them, they likely aren't compatible with Comfort Access.

[BPMSport]

Originally Posted by SilverSlug

Ah okay, all of your fobs are Chinese style replicas?

Only Comfort Access fobs have removable batteries, the non-Comfort Access fobs do not.

So, if your Chinese fobs don't have them, they likely aren't compatible with Comfort Access.

The non comfort access keys are compatible with comfort access cars, although the CA function obviously won't work.

[Binary420]

Originally Posted by SilverSlug

Ah okay, all of your fobs are Chinese style replicas?

Only Comfort Access fobs have removable batteries, the non-Comfort Access fobs do not.

So, if your Chinese fobs don't have them, they likely aren't compatible with Comfort Access.

I do have comfort access, yes.
The key I'm trying to program in a chinese replica.

However the other key I have is an original comfort access key, on that original CA Key, it still will start the engine, but the remote fob and CA both do not work anymore, since it went swimming in the ocean by mistake.

So the original CA key starts the engine when I insert it into the slot,
and all the other keys I attempt to program will also start the engine when inserted into the slot.

However, I am no longer able to run the DME CAS Sync operation. It fails every time.

besides programming the key to the car with the scan tools, is there any other procedure to sync / re-learn the remote fob portion of a key?


Also, there is a company on amazon which sells a 2 pack of non CA keys, as well as CA compatible keys. I think the CA keys are like $15 more for the 2 pack compared to the non CA

Those are the keys I am trying to make work with the car.
link below.

https://s.binary.lol/CAcompatibleKey

[Binary420]

Sorry, my previous post was a bit jumbled.

What I meant was, once you program a new key using a professional immobilizer / programmer tool, via the "key learning" menu, and it finishes successfully saying "now try to start car".

Once that is finished, and key can start the engine, should the remote fob / CA work immediately / automatically as well? Or is there an additional step to make that work after making the engine startup work?

And 1 more question,

If you were to perform key learning (adding a new key) while there is no battery / dead battery inside the key,
would that possibly have an impact on the remote part of the key still not working even after replacing the dead battery?


That may potentially be my issue. because I can't be sure whether or not the battery was dead in the key or not..

I never tested them, but after programing the key, and seeing that it started the engine, but didnt have any remote functionality, I thought maybe the batteries were dead so I replaced them with new definitely good batteries, and still got no remote response from the keys.

But yet they still start the engine just fine.

So maybe the battery was dead during the initial programming of the key? I assume since the remote functions dont work with a dead fob battery, maybe the programming of the fob part doesnt work either with the dead fob.

I had assumed that it wasnt gonna be an issue. I figured even if the initial batteries were dead, surely once replaced, the car would resync it to the car as soon as i put it into the slot and started the engine.

does anyone know how the cas3+ works well enough to explain whether or not programming a new key while the battery inside the key is dead would cause the remote lock / unlock to never work even after replacing the battery inside?
And if that is in fact the case, and since you can only "marry" a new virgin key 1 time,
then what are my options as far as making that key fully functional.

If I initially programmed it as a smart key (which it is so long as smart key means CA key..) but during key programming, the battery was dead in the key, would that key then be useless, or his there any way to "re sync" the remote portion of the key?

Is that what the Sync DME / CAS option I mentioned before does, or otherwise what is the procedure to re-learn a key which has already been devirginized and is able to start the car but fails to lock / unlock remotely

[pjk380]

I would suggest you contact Bryce at Bimmerscan. I picked up a second CA key from him. He is great and might be able to help you get it sorted out.

My 2010 M3 only came with one CA key and I wanted a second CA key. I didn’t want to buy a key from the dealer and I found Bimmerscan in MV.

[dpaul]

Originally Posted by Binary420

Sorry, my previous post was a bit jumbled.

What I meant was, once you program a new key using a professional immobilizer / programmer tool, via the "key learning" menu, and it finishes successfully saying "now try to start car".

Once that is finished, and key can start the engine, should the remote fob / CA work immediately / automatically as well? Or is there an additional step to make that work after making the engine startup work?

And 1 more question,

If you were to perform key learning (adding a new key) while there is no battery / dead battery inside the key,
would that possibly have an impact on the remote part of the key still not working even after replacing the dead battery?


That may potentially be my issue. because I can't be sure whether or not the battery was dead in the key or not..

I never tested them, but after programing the key, and seeing that it started the engine, but didnt have any remote functionality, I thought maybe the batteries were dead so I replaced them with new definitely good batteries, and still got no remote response from the keys.

But yet they still start the engine just fine.

So maybe the battery was dead during the initial programming of the key? I assume since the remote functions dont work with a dead fob battery, maybe the programming of the fob part doesnt work either with the dead fob.

I had assumed that it wasnt gonna be an issue. I figured even if the initial batteries were dead, surely once replaced, the car would resync it to the car as soon as i put it into the slot and started the engine.

does anyone know how the cas3+ works well enough to explain whether or not programming a new key while the battery inside the key is dead would cause the remote lock / unlock to never work even after replacing the battery inside?
And if that is in fact the case, and since you can only "marry" a new virgin key 1 time,
then what are my options as far as making that key fully functional.

If I initially programmed it as a smart key (which it is so long as smart key means CA key..) but during key programming, the battery was dead in the key, would that key then be useless, or his there any way to "re sync" the remote portion of the key?

Is that what the Sync DME / CAS option I mentioned before does, or otherwise what is the procedure to re-learn a key which has already been devirginized and is able to start the car but fails to lock / unlock remotely

1) "Sync" DME and CAS has nothing whatsoever to do with keys. Recognition of keys is 100% a function of CAS.

2) For the MSS60, DME/CAS "sync" is established by writing the same 128 key (the "SK") to each module. For the DME, that can only happen at the factory. You cannot do that with BMW standard tools or ISTA. That simplifies things a bit but close enough for now.