Aftermarket activity

Industrialization of innovative projects

Our other plants
Back to the list

NOx sensors

The advent of the autonomous car has highlighted the fundamental importance of having good sensors. That being said, we have long been committed to providing effective – and reliable – sensors to our customers. So whether you are looking for engine and transmission sensors, or for comfort and safety – not to mention emissions and e-mobility – you should definitely take a look at our range.

Share

Back to the list

Share

NOx
sensors

Also called NOx probe, the NOx sensor is an electronic device positioned in a vehicle’s exhaust system. It detects and measures the concentration of nitrogen oxides in exhaust gases. Nitrogen oxides are pollutants produced mainly by internal combustion engines. NOx is formed when fuel burns at high temperatures. They are harmful to the environment and human health, contributing to air pollution, smog, and acid rain.

Modern vehicles are fitted with NOx reduction systems, such as catalytic converters and selective catalytic reduction (SCR) systems. The NOx sensor helps to regulate these systems to optimize their efficiency and reduce NOx emissions.

In addition, if the NOx sensor detects abnormally high NOx levels, it can send a signal to the dashboard to warn the driver of a potential issue with the engine or exhaust system, requiring an inspection or repair.

Technology
Technical information
Frequently asked questions
Resources
Technology

The technology used in an NOx sensor is based mainly on electrochemical principles and specific materials that detect and measure nitrogen oxides in exhaust gases:

  • Materials: use of ceramic materials, mainly yttrium-stabilized zirconium oxide, due to their ionic conductivity properties at high temperatures;
  • Electrochemical cell: made up of platinum electrodes and a solid electrolyte, used to detect nitrogen oxides (NOx) via electrochemical reactions ;
  • Measurement and reference chambers: the sensor includes a measurement chamber which is exposed to the exhaust gases and a reference chamber which is used as a point of comparison.

Technical information

SYMPTOMS

The following symptoms are frequently associated with the failure of an NOx sensor:

  • Engine indicator light;
  • Specific warning messages;
  • Poor engine performance;
  • Increased emissions;
  • Increased fuel consumption;
  • Unusual smell of exhaust gases;
  • Selective catalytic reduction (SCR) system not working correctly.

DIAGNOSTIC PROCEDURE

It is important to visually inspect the NOx sensor in order to determine whether it is faulty. It is therefore strongly recommended that the following components are checked:

  • The cables (for damage and/or poor connections);
  • The electrical connector (for loose connections).

It is also possible to use a multimeter to check that the sensor is working properly, by testing the continuity and resistance of the NOx sensor circuits. It is advisable to compare the readings with the manufacturer’s specifications to check whether they are within the normal ranges.

If this is not sufficient, the use of an OBD diagnostic tool is recommended to identify the fault codes associated with the NOx sensor:

  • P2200: NOx sensor, bank 1 – performance issue;
  • P2201: NOx sensor, bank 1 – signal out of range;
  • P2202: NOx sensor, bank 1 – low signal;
  • P2203: NOx sensor, bank 1 – high signal.

The fault codes may vary depending on the manufacturer.

If the preceding tests are inconclusive, your vehicle’s NOx sensor needs to be replaced.

CAUSES OF FAILURE

An NOx sensor may no longer be working due to:

  • The accumulation of soot or carbon;
  • Electrical issues;
  • Wear or aging;
  • Chemical contaminants.

INSTALLATION INSTRUCTIONS

To ensure fast and efficient installation, please refer to the following instructions:

  1. Locate the positioning of the NOx sensor on the vehicle.
  2. Disconnect the vehicle battery’s negative terminal.
  3. Access the NOx sensor and disconnect its electrical connector.
  4. Apply a penetrating lubricant (such as WD-40) to the threads in order to facilitate the removal of the NOx sensor.
  5. Also apply a penetrating lubricant to the threads of the new NOx sensor in order to facilitate its installation.
  6. Screw in the new NOx sensor, but do not overtighten as this may damage the sensor or the thread.
  7. Reposition the connector and the battery’s negative terminal.
  8. If necessary, connect the diagnostic tool to clear any fault codes.

INSTALLATION TIPS

As the NOx sensor is essential to the correct operation of the vehicle, it is important to follow certain advice in order to prolong its service life:

  • Maintenance of the exhaust system and injectors is important, as carbon deposits can damage the sensor over time.

PREVENTIVE INFORMATION

The above items are provided for information purposes only. They do not replace the advice of a qualified technician or mechanic. We strongly recommend that you consult a professional if you are unsure of what to do. Otherwise, we cannot accept responsibility for any damage to your vehicle.

Frequently asked questions
What symptoms should I look out for?

If you notice an engine indicator light on your dashboard that indicates an issue with the emissions system or other engine components, then it would appear that the NOx sensor is in a critical condition. It is likely that the vehicle has reduced engine power, slow acceleration, or misfiring. Your vehicle may also emit more smoke than usual, as well as nitrogen oxide (NOx) emissions, which may cause it to fail emissions tests. A faulty NOx sensor also increases fuel consumption. The engine may not run optimally, resulting in inefficient use of fuel. The vehicle’s exhaust gases may also have an unusual or stronger smell due to increased pollutant emissions.

How to identify the fault?

Firstly, we strongly recommend that you visually check the NOx sensor, and more specifically the cables and connections, in order to detect any signs of damage, corrosion, or poor connections.

Secondly, you can use a multimeter to test whether your sensor is working properly. By doing this, you can check the continuity and resistance of the NOx sensor circuits. It is advisable to compare the readings with the manufacturer’s specifications to check whether they are within the normal ranges.

In the event of force majeure, we will ask you to use an OBD diagnostic tool to identify the fault codes associated with the NOx sensor:

  • P2200: NOx sensor, bank 1 – performance issue;
  • P2201: NOx sensor, bank 1 – signal out of range;
  • P2202: NOx sensor, bank 1 – low signal;
  • P2203: NOx sensor, bank 1 – high signal.

The fault codes may vary depending on the manufacturer.

If the preceding tests are inconclusive, then it would appear that you will need to replace your vehicle’s NOx sensor.

Why does my NOx sensor need replacing?

There are many possible reasons for NOx sensor failure. These include obstruction of the sensor by soot or carbon deposits from the exhaust gases, which disrupts its measurements. Damaged cables, loose connections, or issues with the sensor’s electronic circuit can cause malfunctions. Like any component, the NOx sensor can wear out or deteriorate over time, thereby losing its effectiveness. Exposure to chemical contaminants in exhaust gases can damage the sensor and affect its performance.

What are the installation instructions?

We recommend that you follow the steps below to replace your NOx sensor as efficiently as possible and to minimize the risk of any error:

  1. Locate the positioning of the NOx sensor on the vehicle.
  2. Disconnect the vehicle battery’s negative terminal.
  3. Access the NOx sensor and disconnect its electrical connector.
  4. Apply a penetrating lubricant (such as WD-40) to the threads in order to facilitate the removal of the NOx sensor.
  5. Also apply a penetrating lubricant to the threads of the new NOx sensor in order to facilitate its installation.
  6. Screw in the new NOx sensor, but do not overtighten as this may damage the sensor or the thread.
  7. Reposition the connector and the battery’s negative terminal.
  8. If necessary, connect the diagnostic tool to clear any fault codes.
What tips should I use to extend the life of my NOx sensor?

As sensor specialists, we recommend that you apply the following recommendations to prolong the service life of your NOx sensor:

  • Maintenance of the exhaust system and injectors is important, as carbon deposits can damage the sensor.
Resources
This tab contains all the documents available relating to NOx sensors.
Summary sheet
Find out more about NOx sensors.
Download

Other products

Exhaust gas temperature sensors

Oxygen sensors

DPF sensors