Oxygen Sensor 11787516150,11787521705,11787512985,11787516149 for BMW

How does a NOx sensor work?
The sensor is made up of a Nernst cell with a current flowing through. This corrects the air/fuel ratio to λ=1. A second cell, usually made of ceramic with a layer of rhodium, breaks down the oxides of nitrogen into nitrogen and oxygen. The NOx controller – usually closely positioned to the NOx sensor – calculates the level of oxides of nitrogen present in the exhaust gas, and sends that data to the SCR controller. The SCR controller then adjusts the amount of diesel exhaust fluid injected into the SCR catalyst, which in turn transforms excess oxides of nitrogen into water and nitrogen.
NOx sensor
An oxides of nitrogen sensor is used to monitor the levels of oxides of nitrogen that a vehicle emits to ensure it is compliant with emissions regulations.
Oxides of nitrogen (otherwise known as NOx) are pollutants that have both environmental and health impacts. NOx usually refers to nitric oxide (NO) which becomes nitrogen dioxide (NO2) when it combines with oxygen under high temperatures. This reddish-brown gas makes summer smog look brown and hazy in high-traffic areas.
The gases are poisonous and highly reactive. They can affect and contribute to respiratory infections and asthma, especially in children, as well as cause detrimental effects to local ecosystems and road visibility.
Controlling the levels of NOx emitted into the atmosphere is incredibly important, which makes the NOx sensor a vital vehicle component.