In this part of the entry – example of an incorrectly working VANOS.
In the specific problem case, the error message regarding the VANOS position was recorded several times but did not return after dynamic driving. At the same time – there are problems, no doubt!
In the image – general information of both VANOS. In the bottom part, a wavy curve of light green color: PWM of the exhaust VANOS valve (Axis 3)

PWM of both valves, zoomed in (Axis 3)

Compared to the correct PWM (which jitters in the range of 1 .. 2%), this time, the jittering reaches 15%!

Required (absolute) position (in brown color) and the actual position (black color) of the exhaust VANOS (Axis 2):

Significant – jittering reaches even +/-12%!

In the image – performance of the damaged VANOS during transition processes:

The image shows that VANOS reaches the required position with great effort and inaccuracy, but a stable position is maintained by “jumps”. The error is more significant than +/-8 ..12 degrees.
As I already mentioned at the beginning of the article, to record the error message, non-conformity should be 20%. So – even in case of such an obvious problem – zero error messages, but a range of issues: uneven run and “skittish” idle; fast wear of the Valvetronic system guaranteed.