For your consideration: an OEM Engine Control Unit from a 2001 Audi A4 with 1.8l turbo engine.
This will work on other199, 2000, 2001, and 2002 Audi A4 models with the 1.8l or 2.0lt engine as well, but please match your ECU code exactly to 8D0 997 559 CX before purchasing.
If your vehicle is year 2000 or later, this will need to be reflashed by a dealership to match your current immobilizer, or you can have the immobilizer defeated by a tuner.
This will be well packaged and shipped promptly. Please email any questions you may have before purchasing. Every attempt is made to ensure a positive transaction and if for some unforeseen reason you are not fully satisfied I do ask to be contacted before feedback is left. Thanks for looking and happy motoring!