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Key Fob coding syncing

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by beerglass, Oct 17, 2010.

  1. beerglass
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    beerglass Member

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    [Oct 17, 2010]
    Hi all

    My key fob failed a few weeks back and I couldn't fix it. I took the key to Audi and they also confirmed the key fob is dead and cannot be re-programmed. The key still starts the car but the remote lock/unlock doesn't work.

    So I brought a brand new key fob off Ebay which has been cut and programed for a Audi A3, but never used.

    I took my old key fob apart and it looks like the key itself doesn't attach to any of the circuit board inside. So I took both the new and faulty key fobs apart and swapped the keys over. Now the key will not start the car, so somehow the key is coded with my car. How does this all work ?

    Can I do what I'm trying to do here ? Swap the keys over and re-program the key fob part to remote unlock/lock the car ? The Audi manual talks about re-syncing the key, I tired this and failed.

    Any idea's please ?

    Thanks



    I took the
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  3. BASS 666
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    BASS 666 BMW aye right dead on..

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    [Oct 17, 2010]
    the new controll unit you bought needs to be programed to your car by audi or someone with the right set up to do it.
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  4. NHN
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    NHN Retrofitter - Audi - VW - Skoda - Seat Site Sponsor VCDS Map User

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    [Oct 17, 2010]
    You need to take the immo chip from the top of your old key & stick it in the new key, its a pita job to do as the immo chip is inside a glass capsule which is glued in place & takes ages to grind out with a thin stanley, the glass is very very delicate & once cracked is knackered, but can be done, as I have on multiple cars.

    Butttt, your problems dont stop there, the A3 & A4 key remote parts use different signalling so arent interswappable as my tests with an A4 B6 proved before.

    The remote functions & immo are completely seperate from eachother, the key has 2 seperate systems in place that do not work with eachother.

    Also an A3 key immo wont work with an A4, fact, so you cant reprogram it anyway, also used A3 keys are useless for immo aswell as they have megamos 48 immo chips in encoded to the 1st car only, with brand, vin & then with the car at the dealer.
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  5. BASS 666
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    BASS 666 BMW aye right dead on..

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    [Oct 17, 2010]
    thats what i was gonna say. ha ha.
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  6. beerglass
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    beerglass Member

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    [Oct 17, 2010]
    WOW
    Wish I never asked now 8)

    So what your really saying is the A3 key is no good.

    Whats the best option to replacing the key ? Buy a A4 key off ebay and try again or buy a new key from Audi stealers ?

    Thanks again
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  7. NHN
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    [Oct 18, 2010]
    If you're confident enough then buy an A4 key of ebay & swap the immo over, whichever way you go tbh you will need a new key regardless how you get it working, so I'd try the 1st option of swap immo over, but be warned, take your time, patience needed immensely & be very very delicate, took me ages to swap mine over on few cars, broke 1 but this was in the 1st instance & since have been fine.
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  8. beerglass
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    beerglass Member

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    [Oct 18, 2010]
    Silly question but where is the immo ?
    I cant see it. I take it its a small RFID chip
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  9. NHN
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    [Oct 19, 2010]
    Its in the top of the key, hidden & need to remove the cover to see it, then decide if you want to dremel the surrounding area down to get it out, I used a thin blade & slowly worked away at the glue surrounding it.
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  10. beerglass
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    beerglass Member

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    [Oct 20, 2010]
    Hi

    I see the immo is inside the bottom half of the key fob. So I replaced the bottom half of the key with the blade and it works. So as long as the bottom half of the key fob and the blade is paired it starts the car.
    But what about coding the remote itself. You said the A3 key wouldn't code because its different to the A4. The circuit board on the A4 and A3 key fobs read 289482 A6 BA and 289482 A9 BA.

    So the difference is the A6 and A9 is this the difference and where it will not program using a VAG COM and work on the A4 ?

    Thanks again for all this help.
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  11. NHN
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    [Oct 20, 2010]
    Ah yes the older style key that comes in 2 halves, it was in the key somewhere huh :p

    Hey why not try to pair your remote then, but from our tests with A3 & A4 specific keys it didnt work.
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  12. kai hunterwood
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    kai hunterwood New Member

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    [May 18, 2013]
    hey NHN,

    iv got a 56 plate a3 2.0 tdi and just brought a second hand key off ebay with the same part number. do you know if audi will be able to code it to my car?

    cheers kai
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  13. NHN
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    [May 18, 2013]
    Nope, if the immo chip is used then its no good to you except for locking the car.
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  14. kai hunterwood
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    kai hunterwood New Member

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    [May 18, 2013]
    thank you very much,
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