A FEW DAYS AGO DURING MORNING START UP CHECK ENGINE LIGHT LIT UP. AFTER SCANNING FOR CODES IT SHOWED P0170 FOR "FUEL SELF ADAPTATION AT IT'S LIMIT" OR SOMETHING LIKE IT... I RESET THE CODE AND AFTER FOUR DAYS I HAVE THE SAME PROBLEM. THE FRONT O2 SENSOR WORKS OK ON HOT ENGINE, REAR O2 IS KIND OF "SLOW" WHAT DO I DO CHANGE MASS AIR SENSOR ? IT'S EXPENSIVE!
PS. P0170=LEAK IN INTAKE AIR,FUEL INJECTORS OR EVEN WORN ENGINE, BUT NOT AT 37K.

I assume your car is a 1997 from the check engine code. The problem is a severe lean fuel mixture. Almost all 97 M104 engine are having problems with Mass air sensor. If your car is 1997 it should be under warranty.
List price is $500 for part.

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MERCEDES BENZ MASTER GUILD TECHNICIAN (6 TIMES)
ASE MASTER TECHNICIAN
27 YEARS DEALER M.B. Shopforeman
190E 2.3 16V ITS SCCA racecar