VW/Audi IMMO III SKC Retrieval

Below is the instructions on pulling the secret key code (SKC) from the ECU of a B6 A4 (2002-2005). The procedure should be similar for all VW/Audi/SEAT/Skoda vehicles that utilize VW's generation 3 immobilizer. This will primarily be model year 2002 and newer vehicles.

This information is documented in other places, but doesn't provide a way to verify the information retrieved, or do a good job of really explaining what you're doing. There were also guides for getting the information that just didn't work. So, I've tried to fix that by taking the process and writing up my own guide for it, which is what is below. I take no responsibility for any harm that comes of this, and doing all of this is at your own risk. While nothing should happen, there are always risks involved. Total time for this is probably 10 minutes, providing you have the right things to work with.

What You'll Need

1. Licensed version of VCDS (VAG-COM)
2. Computer/Laptop/Tablet to use with VCDS
3. VAG K+CAN Commander
4. OBD-II Cable - You should be able to use VCDS cable (see here), or you could get a generic one from eBay/China
5. Your Car

What You'll Do

First, we're going to use VAG K+CAN Commander. Make sure that it works properly and the drivers are installed. Plug the cable into the OBDII port and also into the computer. Open up the software and make sure it recognizes the cable. If you're on Windows Vista or Windows 7, you may need to run it as an administrator. In the bottom left, select the connection type to be K-Line, as seen below, and then click the Engine Control Unit button.

Choose your ECU type, mine was the second option in the drop down list (VAG-ME7.1.1/7.5/7.8 wakeup pattern 01). After that, click read EEPROM, allow it to select the range automatically, and wait a few seconds. From there, it should give you a bunch of info.

Below is a picture similar to what you should see after it is done reading the EEPROM. I've highlighted two things in the picture. One item is the two bits that are the SKC, address 32 and 33. You can take these, reverse them, and put them into a HEX to DEC converter and get your SKC. So, in the picture, my SKC is C0 01, so to convert it, I would enter 01C0 into a hex->dec converter and take the result as the SKC. The other item highlighted is the Login, which is the same thing as converting it yourself. I'd just verify that it is correct manually, it doesn't take long to do.

From here, we are done with VAG K+CAN Commander, and you should have your SKC now. All I would do now is verify it using VCDS. So, plug in your VCDS cable (if you weren't already using it) and open up VCDS. You can verify the SKC in two places, one provides feedback, the other doesn't. We'll test it out on the ECU, as it provides feedback on the pin being correct or not. So, open up the engine controller in VCDS. Once it is open and finished populating the fields, click on "Coding II - 11"

It will bring up a screen with 5 '0's in it, here we will use the SKC we pulled. First, put in a '0', then the 4 digit pin that you found earlier. As you can see in the picture, my pin was only 3 digits, so I added another '0' before it, so it is 5 digits total.

If it is the correct pin, when you click "Do It!", you'll be greeted with the following popup.

If it was incorrect, you'll see this instead.

It will then take you back to the ECU controller screen. You'll see here though that there is also a security access button. You may think that this is where you would enter the SKC, and if you click it, you get a similar login screen, and it even mentions entering the SKC on it, or using a 7-digit SKC. However, this isn't where you want to put the SKC in, it will fail, even if the pin is correct. I know this because I tested out my SKC several times in this very spot, leading to much frustration on my part.

The other place you can test out the SKC is through the instrument cluster controller. Close the ECU controller and open up the Instruments controller (number 17). Here, you test out the SKC via the same method, just the button is labeled differently. Click the "Login - 11" button, enter the same 5 digits you used for the ECU, and click "Do It!". Here though, you get no feedback on the screen. I noticed that my immobilizer icon lit up on the dash when I was logged in, and then went out when I closed the controller. This may be your only verification when using the instrument cluster to test the SKC.

That is it, you are done and can now do pretty much anything you want with VCDS and avoid the dealer for things. If you want to use this information to program new keys to your car's immobilizer, Ross-Tech has a nice how-to video on Youtube for this, see here. They also have a nice video on pairing a new ECU or Instrument Cluster to your car as well, right here. Now go enjoy your new-found dealership freedom.