Mercedes-Benz Q Codes Information for NOx Sensor Replacement

Josep Technical Support Specialist New York Posted   Edited  
2012 Mercedes-Benz ML350 Bluetec 4Matic 3.0L (642.826) 7-spd (722.9)
Add-Blue Message In Cluster /Limited Starts


  1. Remove the NOx sensor from mounting bolts.
  2. Read the NOx sensor part number and Q level located on the back side of sensor the last 3 digits on right hand lower part of the number.

Q Level NOx Sensors Q1 & Q2 can not be mixed with levels Q3, Q4 and Q5, Q3, Q4, and Q5 level NOx sensors are interchangeable and can be used in any combination. There is no need to have the same Q level NOx sensors upstream and downstream as long as the Q level is 3 or higher.

Ensure when installing a new NOx sensor that the Q level of the sensor is Q3 or higher