Having gone through a Mini rollercoaster of troubleshooting and cash, I'd like to share the story and hopefully save someone some time and money. The vehicle is a 2008 Clubman S six speed. One day while driving it went into limp mode, fortunately close to home, and it was driven back. As I was going to start it up to get it in the garage it would crank but not catch. A scan with the code reader (Schwaben) showed a code A0B3 from the CAS and the DME would not talk or show up at all. The code would clear but come back after a start attempt. Having read about how the DMEs fail all the time, a used one was sourced and sent out for cloning. Once back, it was installed and now the scanner could talk to it but the engine would still not start, just turn over but it gave a code 2BD3 (power supply 2 driver CY320). The CAS was free of codes. This code occurs when an expected voltage is not present or low. The particular one in this case is the one that drives all the engine sensors such as the intake pressure, MAF, boost sensor, etc. A 5V dc voltage is applied to each sensor and the return voltage from each sensor is the value the sensor is portraying. My source voltage was 2.5V dc as read on pin 37 on the X60231 harness, or any orange wire going to an engine sensor. This voltage was either being loaded down or not getting made properly by the DME. You can unplug sensors until the voltage comes back and that will tell you which one it is, or you can unplug the harness and see if the voltage is good from the DME with no load on it. I unplugged the harness and still 2.5V dc. This pointed to a bad DME and another unit was sourced and cloned, you can start doing the money math now.
Round two. The new DME was plugged in and the same result, 2.5V dc on pin 37 and code 2BD3. Studying the schematics in the Bentley, I noticed another sensor that got power from this same source, but was on a totally different harness..... the accelerator pedal. It was disconnected, pin 37 voltage returned to 5V dc, and the engine started up. Of course, this creates a different set of codes and the car is not moving without a gas pedal. I opened up the unit and found that there is a copper bar that moves back and forth in front of a plastic window to generate the position signal (hall effect sensors). The copper had rubbed enough that copper dust was all over the window creating a short on the signal and loading down the source voltage. Cleaned it up and the car is running once more.
In summary, two issues. A bricked DME followed by a faulted sensor. Did the gas pedal short first and cause the original DME to fail or was it all coincidence?
Either way, I hate reading posts with no solutions or much to go on so I hope this helps someone since the codes are vague and do not pin point the fault.