BMW NOx Sensor and SCR System Guide

Measures the level of NOx in the exhaust past the diesel particulate filter, part of your BMW’s SCR system, includes control module

Diesel powered vehicles, particular turbocharged diesel engines, have very high exhaust gas temperatures due to the pressure and heat created by the ignition cycle. This is intended to reduce the amount of soot released by the engine and to create a more efficient burn. However, the side effect of this is NOx emissions (nitrogen oxide) which is harmful. To reduce NOx emissions modern diesel engines are quipped with an SCR urea system. Urea is sprayed into the exhaust system upstream and the chemical reaction between NOx and the urea creates molecular nitrogen (N2) as well as water which is of course much better for the environment.

The NOx sensor detects the level of nitrogen oxide in the exhaust which in turn ios used to control your BMW’s SCR system. Failure of this sensor will result in a check engine light or may even prevent you from starting your vehicle.