engine management fault
I'm not a Mercedes man but this tells me that either the balance shaft is out of sync with the engine or the balance shaft sensor is bad. Have you noticed any abnormal engine vibration at any speed? I would have this checked at your favorite Mercedes shop just to be certain, an out of whack balance shaft can severely shorten engine life.
Do you have a code from a scanner? They can be very specific and will help decide who can look at it. Do it right away, it could be serious.
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