Intermittent Check Engine Lights
 

Gilly: I have had some CEL's over the last few weeks, on my 1999
ML 320 and my code reader always shows them to be PO 170 or PO 173 .... Fuel Trim, Bank One or Bank Two.. The car is running perfectly; are these lights indicative of a pending problem with the EGR pipe or MAF or something of that kind... thanks, Ben Carter

MORE than likely the MAF sensor. If you can read freeze-frame data for the CEL illuminating event (fault code), then look and see what the fuel-adaptation number was. Usually you see it maxed out, up around 1.31 or so. You also need to be sure that the O-ring at the end of the MAF sensor is installed correctly and no leakage at the end of the intake pipe.

Gilly

ML 320 CEL's
 

Thanks, Gilly ..... I will check that out more specifically. Ben Carter

Air Mass Sensor
 

Its definitely the air mass sensors, I can get them for $200US, half the price off dealer...