Tighten three of the four screws snug and lightly tap on the body to rotate the pot position on the AFM. I would try and achieve less than .7v at idle with engine running. The adjustment has to be with the engine running. The amount of movement required can not be seen, as it it too small. It is so sensitive that MB does not sell the pots separately (though they are available through Bosch).

If around this voltage a small movement makes the voltage go the wrong way, replace the pot. The spot of contact at idle is where they wear out.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician