BRIEF INFORMATION
NOx Sensor
PRODUCT FEATURES
Application
Wide range available for commercial vehicles with different part numbers and suitable for the most common 24 V applications: DAF, Mercedes-Benz, MAN, Scania, Volvo, Renault, Iveco.
Design and function
The NOx sensor comprises a probe and a control unit. Via a cable harness these are firmly connected with each other to form a unit. This sensor unit is installed in the exhaust gas system and is used to recognise nitrogen oxides in the flow of exhaust gas.
The NOx sensor is an important component in the post-treatment system to reduce NOx, which is used in diesel vehicles with urea-based SCR systems (selective catalytic reduction). The sensor enables compliance with the stringent emission values starting from Euro 5 norm onwards. Consequently the NOx sensor guarantees an optimal dosage of AdBlue by the engine system, thus bringing about an effective reduction of nitrogen oxides which are harmful to the environment.
If the SCR system has an upstream and a downstream NOx sensor, the downstream one has the task of monitoring the effect of the SCR catalytic converter.
Mounting
Easy to mount because of 1:1 replacements in OE quality. Installation instructions are supplied with the product.
SCHEMATIC STRUCTURE
The exhaust gas flow resulting from the running of the diesel engine enters the diesel oxidation catalytic converter (DOC) and then the diesel particulate filter (DPF). Once the particulate filter load of the DPF reaches a certain value, cleaning has to be carried out.
Such particulate filter regeneration is automatically triggered and monitored by the relevant higher-level system control unit. What is more, vehicles with an SCR system (selective catalytic reduction) can be equipped in such a way so as to reduce amounts of nitrogen oxide.
With the systematic addition of a reducing agent (AdBlue) to the exhaust gas system, a reaction takes place as a result of which nitrogen oxides (NOx) are converted into nitrogen (N2) and water (H2O). And furthermore, in combination with a cleaning catalyser (an ASC), excess ammoniac (NH3) can be converted into nitrogen (N2).
TECHNICAL DETAILS
| Technical data | |
|---|---|
| Supply voltage | 24 V |
| Measuring range | NOx: 0 – 1500 ppm |
| Operating temperature | NOx: 100°C to 800°C |
| Vibration resistance | Yes |
| Sensor thread | M20 x 1.5 |
| Weight | Approx. 300 g |
Pin 1: Power supply
1 What is a NOx sensor and what is its function in a vehicle?
A NOx sensor measures the nitrogen oxide content in the exhaust gases emitted by the engine into the atmosphere via the exhaust gas aftertreatment system
2 How can you choose the right NOx sensor for your vehicle?
Read the part number of the sensor to be replaced or look up the OE reference from the relevant EPC based on the VIN (vehicle identification number).
3 How can we avoid diagnostic errors when considering replacing a NOx sensor?
Check the system before replacing the NOx sensor. Check the system after installation of the new NOx sensor
4 What happens when driving with a defective NOx sensor?
Once the fault has been detected, the vehicle's control unit starts a manufacturer-specific countdown based on the applicable emission regulations. This process soon leads to a continuous reduction of engine torque and vehicle speed over a designated period of time, thus giving the driver the opportunity to call in at the nearest specialist workshop and have the exhaust problem rectified.
5 What is the most important factor that can shorten the service life of a NOx sensor?
Inadequate engine maintenance is one of the main factors that can shorten the service life of a NOx sensor. Over time this can lead to excessive engine wear, which in turn results in exhaust gas contamination, e.g. an imbalanced air-fuel mixture, which will then directly have a negative impact on the exposed sensor head.
6 Which components can be affected by a defective NOx sensor?
It is important to note that failure to replace a defective NOx sensor over time can have serious and irreversible consequences for expensive components of the exhaust aftertreatment system, such as the DPF (diesel particulate filter) or the SCR (selective catalytic reduction).