The steering angle sensor is what kept being diagnosed as the main culprit, then after replacing it they would conclude that it was something else and replace it section by section. I'm not kidding when I say it was completely replaced several times with no improvement until the tech replaced the screws holding it together. It is/was the rocking rocking/play in the steering column which would cause it to malfunction. Try this -- with the car on and BAS-ESP light off, try pulling the steering wheel toward you. Or, let the car creep forward in first gear, then pull and push on the steering wheel. There should be NO play in it. If there is play, then chances are that the light will activiate. Ever notice it goes on when you hit a bump or go over speedbumps etc ??