Many times we can read a code & if we have enough information we can make a partial diagnosis. With a GOOD scan tool a good technician can look at all of the engine control modules (3 on this model) & make a better long term diagnosis of exsisting problems. When you look at the module that turn on check engine light it only provides a numerical code that must be translated into real world diagnosis. Looking into fuel system & idle speed (electronic accel) will give a much better idea of problems. The IAT sensor that you have cleaned should be replaced as they go open circuit at times & will trip check engine again.

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MERCEDES BENZ MASTER GUILD TECHNICIAN
ASE MASTER TECHNICIAN
27 YEARS DEALER M.B. Shopforeman
190E 2.3 ITS RACECAR
1986 190E 16V