2022-03-02

How exhaust emissions are regulated

How exhaust emissions are regulated

Due to current discussions about the correct observance of emission values for passenger cars and commercial vehicles, the NOx sensor is becoming increasingly important.

ATOMTEC | 4. September 2020


The NOx sensor is an important component in the complex exhaust system of modern vehicles and makes a major contribution to the control and diagnosis of nitrogen oxide reduction (SCR). Typical installation locations are before and after the SCR catalytic converter.

Incorrect dosing of reducing agents and deviating exhaust gas compositions are precisely detected by the amperometric measuring principle of this sensor. The probe element records the values of the nitrogen oxide content in the range of 0-3000 ppm of the passing exhaust gas. Subsequently, the recorded values are processed by the included sensor control unit (SCU) and transmitted to the engine control unit via CAN bus.

The NOx sensor, or Nitrogen Oxide Sensor, is thus an important interface of the exhaust gas aftertreatment. In case of malfunction of influencing components, among others the urea injection, this can be at the expense of the usual vehicle performance.

If a deviating nitrogen and oxygen load in the exhaust gas is detected, a reduction of the engine performance in the range of 25 – 40% comes into effect. A corresponding fault memory entry follows and the engine control lamp (MIL) lights up. Thus, an immediate replacement of the NOx sensor is necessary to ensure compliance with current and future emission limits.

For the ideal repair we guarantee you with our complete range of high performance, measuring accuracy and direct fit – now for commercial vehicles and of course also for passenger cars!