One problem related to o2 sensor has been reported for the 2012 Mercedes Benz E350. The most recently reported issues are listed below.
My 2012 mercedes E350 has oil contamination of the wiring harness. The oil has also damaged other components in the engine compartment including oxygen sensors; probes and ecu(computer) this is very expensive damage. Mercedes-benz had had recall for this problem in the past but the recall did not extend to the 2012 model year. They need to do another recall for this ongoing problem. This is a major safety hazard, as the car could stall in traffic without warning.