Most modern vehicles are repairable at the corner garage, it just takes being a computer nerd and several thousand dollars in tools. You have to buy a scanner to read the codes and watch the live data (basically as an oscilloscope). If you need to update the firmware, or replace a failed module with a different one, you also need to pay the manufacturer to access their programming software.
A little dated, but a good overview: http://www.drewtech.com/downloads/articles/J2534%20Primer%20...