Why You Should Get the NOx Sensor for Your Diesel

NOx Sensor

No, NOx sensors don’t just belong in the video game “Need for Speed” anymore.

With the current automotive technology advances when it comes to exhaust systems, you’ll find that there are now legal requirements and thresholds that you need to meet. And, you can’t do that without having a NOx sensor.



On the global level, there are stricter environmental controls to decrease the rates of pollution, that’s where your sensor comes in. Keep on reading for our full breakdown of what a NOx sensor is all about, as well as why you must have a functional one.

What Is a NOx Sensor?

In the simplest of terms, a NOx sensor is a device that measures the levels of nitrogen (specifically, nitrogen oxide) your vehicle emits through its exhaust system. 

Yet, you need to understand that the sensor is just a single component of a multi-tiered system, which is the NOx reduction after-treatment system. It’s responsible for sharply reducing harmful exhaust gases, and protecting the environment from the pollution that diesel vehicles with urea-based SCR systems tend to cause. 

Moreover, depending on your vehicle’s make and model, you might have a different set of components present. Generally speaking, a regular system will have a turbocharger, an SCR catalyst, as well as a DPF. As for the NOx sensor, it’ll be placed upstream from the catalyst.

What Does a NOx Sensor Do?

As with any other types of sensors, NOx sensors are responsible for analyzing a vehicle’s emissions, to determine the quantities of nitrogen oxide that are being released into the air. 

They work by using an electro-catalytic mechanism, that allows a specialized material to react with the nitrogen oxide. It’s done by passing a voltage through an electrolyte, the sensor can tell how much NOx is present. The higher the voltage, the higher the level of NOx.

Once the NOx determines the amount of nitrogen oxide, it sends this information off to the SCR system, which is responsible for adjusting the output to meet emission regulations. 

Why Do You Need a NOx Sensor?

Of course, we’ve already mentioned that your vehicle is required by law to not exceed a certain threshold of producing pollutants. However, it’s not only because of the regulation and the harm to the environment that you need a NOx sensor. 

There are annual testings conducted for diesel vehicles, so if you don’t have a NOx sensor in place, you might fail the test. Once you do, you might not be able to renew your car’s license (in some countries) unless you can prove that you’ve decreased your NOx emissions.  

Ready to Fix up Your Car?

We know that learning about a NOx sensor for the first time can be a bit overwhelming. But, once you’ve got the basic foundation of how it works, and why it’s important, it’ll be smooth sailing (or is that driving?) from here on out.

We hope our little guide was able to illuminate the process of NOx sensors. But, if you still need more information, you should check out our automotive resources section for all the tips and car fixing manuals you could need.