To talk to you Audi and delve deeper you need a specific reader for your car (i.e. like odis for the VW group). As most Chinese sellers stop selling the vagcom cable, I use the elm327 as an alternative since it is generic reader with reasonable price (got a bloody ELM327 WIFI OBD2 code scanner from China for $17.99 delivered) that you can learn from.
I downloaded a free TouchScan app during waiting for the ELM327 scanner. Just wait 2 weeks for delivery, plug it in to your car and hook it up to your iphone and be surprised. Note when you plug it in, the lights cycle through a self-test mode until only the red LED is lit up, indicating the scanner communicates with the vehicle. I have WIFI and cannot really see any delays, and am able to track down cam sensors, misfires and lambda /airleaks pretty quick. As for the TouchScan software, it seems like a pretty good deal to me. Here are a few data screen shots that I took yesterday.
So far the ELM327 has paid for itself. And if you are looking for an inexpensive way to read diagnostic codes and troubleshoot audi system errors, I recommend this setup highly – for about 21 bucks, it gives you all the information you need and more!