Hi all,

I have a 2009 standard R56 auto, which currently has a very perculiar set of issues. I have searched around and can't seem to identify the problem.

Overall, there are two types of symptoms:

1. Under certain situations, the car appears to be running on three cylinders
2. Under certain situations, the car refuses to downshift under heavier load.

The symptoms appear under the following scenarios:

- Car in neutral and not moving, under heavier load the car sounds like it is running on three cylinders. However, under partial load the car runs smoothly. This is the same if the car is moving and in gear.

- Car moving in D, under heavier load the car shakes/shudders, bogs down, and refuses to downshift. It almost sounds like it is running rich. Eventually the car downshifts and things return to normal. The shifting problem is better under SD mode, though still persists to a much lesser extent. The shifting problem is resolved if I use manual mode. If the car refuses to downshift, I can use manual mode to shift down.

I have taken the car to a dealership, and it threw up error code 523A.

I have posted a video on youtube to help give you an idea of the symptoms.
www.youtube.com/watch?v=pM2u0kD6XAo

Does anyone have any idea what the issue/issues are? I am completely lost.

Cheers