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audi-a4-b7Tired of looking at your outdated B6 key fob? Well, you're in luck! You can easily upgrade to a newer B7 key fob with simple hand tools and a little patience. Here's how.

First things first, obtain a B7 key fob. These can be found on eBay for around $20, but do your due diligence. Make sure you get one that came from an A4 and not an A6. You can determine this by checking the part number of the fob; a part number starting with 4F0 is from an A6 and will NOT work. The immobilizer chip is soldered onto the board and will interfere with the glass chip that you transfer from your old fob. However, a fob with a part number starting with 8E0 will work. The problem is that many eBay sellers do not refer to the part number; instead, they refer to the FCC ID. The FCC ID you need is MYT4073A. You don't need to worry about finding one with a "virgin" immobilizer chip if you intend on swapping your old immobilizer chip over. Just keep your eyes peeled for a used one that's in good shape cosmetically.

Additionally, If you have a 2002 A4, the comfort control module (CCM) will not work with the the B7 fob. If you wish to do this, you will need to swap in a CCM from a 2003 and up B6.

Comparing the two keys:

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Take your B7 fob and remove the battery cover. It just pries off.

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This will expose three small Torx screws. Remove them.

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After removing the three screws, carefully separate the two halves. The key portion is spring loaded, so it may fly out if you're not paying attention.

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Gently pry the circuit board out.

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Now that the B7 fob is disassembled, we can start taking apart the B6 fob.

Pry under the rings with a thin bladed screwdriver. There is a screw underneath that holds the two halves together.

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Remove this screw and use again use the thin bladed screwdriver to separate the top and bottom portion.

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Take the portion that you removed the screw from earlier and pry it apart. Hopefully, the previous owner of your car didn't have the bright  idea of using Krazy glue to hold the two halves together. I ended up breaking the plastic where the glue was applied.

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Now, we want to swap the transponder chip from our current key fob so that we don't have to worry about programming the immobilizer to work with the key. Just take a small screwdriver or pick and pry it out of the slot that it sits in. Be careful; the chip is made of glass and is only held in place by a pressure fit.

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Take the transponder chip and place in the upper right hand corner of the B7 key fob. I used some hot glue to hold it in place.

Before you reassemble your B7 key fob, you have two options. You can either swap the key blade from your B6 fob or get a new key cut. At first, I chose to swap the key blade, but the B6 blade is longer than the B7 and therefore will not fold into the side. So, I got a new key blade from eBay and had it cut by my local locksmith for about $20.

Once you reassemble your B7 key fob, all that's left is to reprogram the key fob so that it locks and unlocks your doors. You will need access to VCDS for this portion.

From the Ross Tech website:

Channel 021: Remote Control Matching
  • [Select]
    [46 - Comfort System]
    [Adaptation - 10]
    Channel 021.
    [Read]
  • * Choose the memory position you want the new key be matched on by entering it's number (e.g. "3" for memory positon 3).
  • [Test]
  • * Now press any button on the remote you want to match.
    * The meas. block field above will change from Not Recogn. to Recognized.
  • [Save]
  • [Done, Go Back]
    [Close Controller, Go Back - 06]

Note: You can check the current memory positions using Meas. Block 007.

Enjoy your new key fob! Let us know if this guide was helpful.

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Audi A4 B7 image credit to Nico Demattia of QuattroDaily.

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Written by :
David Fresne

David Fresne is a Mechanical Engineering Student at SUNY Polytechnic. He likes to work on his B6 Audi A4 and motorcycle in his free time.


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