Son’s Audi Quattro: Immobilizer Workaround

A number of months back I found a 2002 Audi Quattro Avant (wagon) for my son with the 1.8T engine. Yeah, it’s the only non-diesel vehicle that has my name on the title, but at least it has a turbo. It’s a 20-valve engine, too, and it spools up sweetly!

Audi Quattro Avant (Wagon)

This is the Audi Quattro Avant 1.8T I bought for my son to drive.

Audi Quattro Avant - FrontThis was to be an inexpensive vehicle to keep him moving between locations while he lives in Indianapolis, takes classes, and works with employers while going through Apprentice University. He’s interested in Information Security, a field where one couldĀ get a degree, but frankly the employers care a lot more about experience and certifications, so he’s taking the direct route.

Regardless, this was to be an inexpensive car, and we immediately put about $900 into some things it needed, like a timing belt, some repairs, and an updated head unit with Bluetooth. (Yes, I’ve also recently replaced the clutch, which was another additional expense.) In the spirit of having a cheap car, I realized that we only had one key, so I bought some cheap-o keys with remotes online through Amazon. The remotes weren’t compatible, as it turned out, even though I tried programming the car to listen to them with my Ross-Tech VCDS. I also found out that the immobilizer system is a real PITA and I can’t teach the car to listen to new RFIDs with the VCDS. Drat! I found a local guy who would cut the key blanks to fit, so at least I could get physically-compatible keys without spending a lot of money.

Key Fob, Holder, and RFID Capsule

From left to right: The key fob, the RFID capsule, and the 3D printed holder I made.

Holder with RFID Inserted

After test-fitting everything, I put the RFID capsule into the holder.

I came up with the idea that I could pull the RFID capsule out of the one key we have and hang it on the ignition switch. So, I created a model in FreeCAD, 3D printed it, slipped the RFID capsule into it, and put it in place with a small dab of epoxy. With this in place, I can now start the car with the additional key blades that I had cut. With VWs and Audis, you can always lock/unlock the doors from the driver’s door key lock, so these cut blades give us everything we need for a backup, in case the one key gets lost. Believe it or not, I actually found a key model on Thingiverse that I modified for our key code and I’ve actually unlocked and started the car with a 3D printed key!

The 3D model for the RFID holder is available on Thingiverse, if you’d like to print your own!

RFID Holder Installed

Here the RFID holder has been installed on the ignition switch.

RFID Holder With Key Inserted

3D Printed Key

I 3D printed this key and used it to start the engine!

May the Lord bless you and keep you running on all cylinders!

 

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