Need help 1.6L 2011 Pedal position limp mode
 

A good friend of mine has a 2011 mini convertible (non "S") that has gone into limp mode. She is located on Oahu Hawaii and took it to a local mechanic that specializes in European cars. Error code 2b4e and eb4b, accel pedal sensor. Sensor was replaced with no improvement. Next main computer was re-flashed. Still no joy. Then waited months for a new brain from the factory (programmed specifically for her VIN). Still no improvement. Mechanic does not know what else to do and has thrown in the towel. They reset the code and it drives normal until the first time you step on the brakes. Then back to limping along. She is stuck with a car that won't function properly. I thought I might tap into the combined knowledge of this forum for help. Does anyone have experience with a similar situation or know what else could be the issue? I did try the search function it honestly is brings up so many threads on "limp mode" that I gave up searching through the results after about 5 pages. Thank you in advance.