I have ML 320 Blutec with OM 642 diesel engine.

I have this code per my code reader. I can't even clear this code, it goes away and come back right the way on code reader even if I will not turn a car on. If restarted a car Check Engine will be illuminate again. I have normal driving, no loss power and all work as is. I replaced about month ago EGR valve (what is pain.)
Used start system to adopt a new EGR. Everything was fine until few days back.
its hard fault and no solution.I tried disconnected plugs from MAF and boost sensor and nothing help - Upper limits value components HFM SFi has been exceeded is still there .


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91' MB 350 SDL, with 961 engine and #14 valve head
09' ML320 Bluetec