I have a Sprinter 208 cdi from the year 2005 with a mileage of 303,000 km. After I have eliminated all damage to the engine technology, I had the AU done once. I renewed the following things in advance: LMM, both vacuum control valves, vacuum box throttle valve and the AGR valve cleaned. Filters and oils are new. I drove the car for about an hour at 3000 tours with ARAL Super Diesel before I went to the workshop. Unfortunately the Trübu was located ngwert at the first measurement at 1.1 then at the 2nd attempt at 1.3 and at the 3rd at 1.4. AGR valve is clean and works as far as I can judge impeccable. If I give gas in out of the idle the engine throws out a small black cloud first. Does anyone have any idea why the value is so high? Greeting Dirk