You can look in VagCom/VCDS to determine how close you are to getting the P2015 fault code. In Measuring Block 121, field 4 you can see the resting feedback voltage going to the V157 flapper motor with the
engine off and ignition on. The lowest voltage we have seen thus far consistent with NO check engine light is .380 volts:
If you fall below this voltage, the field 3 display (Bin. Bits) will go to
all zeros and the P2015 code will be set.
On a new manifold or with the Dieselgeek P2015 repair kit installed the voltage in Field 4 is approximately .760:
If anybody sees something different than this please email me or post it here.