Getting Passat B6 key fob enabled with central locking

[MHDxMK5BK]

One of my keys died, one minute ok then the unlock button doesn't work. Checked / replaced the battery put back together then completely dead, even the red LED.

So I recover the transponder chip and buy a new fob for about £32 on ebay.

There are endless posts on YouTube on how to get a key operating with the central locking but none are working for me.

Does anyone know the process?

[MHDxMK5BK]

33429

[DMitch16]

As far as I know the RFID chips in modern key fobs are often set in a glass cocoon to make them waterproof - if you break the glass trying to recover the chip, you nearly always break the chip.

Most 3 button essentially keyless VW fobs from 2005 onwards need reprogramming via the dealer as the ECU needs to communicate with the "Mothership" in Germany as the dealerships no longer see the SKC code which is transmitted remotely over the link between Dealer to VW central computer. Unless you still have it (I do on the original tag attached to the spare key). Some locksmiths / technicians have the necessary software to extract the code from the Immobiliser / ECU.

If the old key went dead all of a sudden and it was not the battery but circuitry inside you need more than just to stick the RFID chip back into a new key fob. It will need correct programming (by dealer or specialist) and not pairing which is a different process.

This is my understanding so I welcome a more expert opinion.

[martin1810]

There are two factors involved.
Immobilizer and comfort function (central locking etc).
This fault seems to be just comfort function as I presume the old key could still start the car.
Given this, it should be possible for a professional locksmith to use the original chip and get a new key to talk to the car.
The comfort functions are not so dependent on Secret key codes etc.
Can the new key start the car with the old chip in it?
The danger of attempting programming yourself is that you may accidentally delete stored data for all keys during the process and then you are in a mess.

[MHDxMK5BK]

Thanks gents, let me share what I've learnt as I got this working today.

The central locking bit is easy, that's auto locksmith easy not layman easy. You need the device to talk to the computer and they are specialist, to me anyway.

My new after market remote was fine and the guy couldn't crack the car's codes with the programs he ran so couldn't set up the new transponder. Therefore he used the one from my old key (old key quite buggered in the process) and opened the new key (wasn't glued so was ok) and broke out the new chip which was glued into it. Dab of glue to hold my old chip into the new key and all is well.

I did find out that if you loose all keys then something major needs to be swapped out (ECU maybe) as the processes require the ignition on and that requires a working key. He did manage to extract, via a Brute Force bit of software I think, one of the codes but didn't have the one from the original tag Crasher mentioned.

So you were both spot on there, he reused the transponder and swapped the key. I think he tried the other methods as there was a risk of damaging the key opening it up but all was ok in the end.