You might get a response if give the model of car. Most folks don't have a clue on m62!! I guess that you are talking about a SLK230 or C230K??
If the clutch is engaged the "kompressor" will be at maximun controlled boost. The clutch has NOTHING to do with boost control as it stays engaged all of the time. Boost on M111 Kompressor engines is controlled by the recirulating air flap & info from the ME computer.
Are you getting a code like P0802??
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