Originally Posted by
az3579
If your steering wheel is straight and the car tracks straight, an alignment probably isn't going to make the error go away. The steering angle implausible message only comes up if the value of the maximum allowable steering angle is exceeded or if the sensor isn't getting expected values, either from being miscalibrated or being faulty. The sensor is calibrated as such to allow for the alignment to be slightly off. Anything that would trigger the error would be a serious misalignment and would be noticeable in the steering wheel position when the car is driving "straight". With this being said, an alignment doesn't hurt anything, so you might as well do one anyway if you haven't already since buying the car.
If the brake pressure sensors were the cause, you wouldn't be getting the steering angle implausible error.
Personally, I dislike DIS and avoid using it whenever possible. Instead, I use the BMW Standard Tools suite of software along with ISTA-D to diagnose issues. Do you have INPA installed on your PC? If so, you can use that software to directly read the steering angle sensor and see what values it sees when the steering wheel is in a certain position. This could give you a clue as to whether the sensor is reading properly, and this also allows you to manually calibrate it.
On a final note, an old battery causes really weird electrical issues in our cars. Check the date on the battery and make sure it's not too old.