Mercedes Benz repair: auto repair, mecedes, 2000 e320

Question
how do you fix a fuel trim malfunction on 2000 e320 mecedes

Answer
 First of all this means that you have a code po170 or po173 on the ME (motor electronics control unit). I would need to know a little more information to guide you in the correct path.

what exactly does the code read in its entirety.

example PO170 (Fuel trim self adaptation at idle or at partial load?