right.

So, my experience with this comes from much different cars, but since no one else is jumping in here (hint), I'll say what I can.

If you made a homemade jumper to pull codes the ECU may be sensitive to the timing of engagement and dis-engagement of your jumper. (ie.. with key in, w/o key in and in what position etc..)

If the method of actually removing the codes requires the turn of some screw.. you may need to do that at a certain time as well, then return the screw to its original position.

I guess what I'm trying so say is: where is the factory method of extracting these codes? I can't seem to find it in the FSM and Mercedes must have a factory version of your jumper, correct?

Edit: answered above.

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