Mercedes Benz repair: EGR - Check engine light, engine wiring harness, mercedes benz

Question
My 1995 S320 keeps turning on the check engine light. My Mercedes trained mechanic says the faults codes point to the EGR. He has cleaned the EGR (and says there is nothing worng with it). On one occasion, he even replaced the EGR with a new one. Once he has reset the computer, it takes around 100-200 miles for the check engine light to go back on (always a fault code for the EGR). This has happened every time for the last 5 restes. Any ideas?

Answer
Did he clean the EGR passages?

I have repaired this issue 50% of the time by replacing the air mass meter, other times the engine wiring harness was the issue.

MB Engine Wiring Harness Failure
http://www.mercedesshop.com/shopforum/showthread.php?p=927185#post927185


Vehicle: 1995 Mercedes Benz S 320
Part: Air Mass Meter
-----------------------------------------
  Air Mass Meter
  Engine: -12-073222
----------------------------------
   Air Mass Meter
  Engine: 12-073223-

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