The new NOx Sensor ensures accurate Urea dosing and can replace the OE sensor directly.

An essential part of modern trucks

A NOx (nitric oxide) sensor is typically a high-temperature device that measures the level of oxides in exhaust systems, which is strictly regulated by authorities in all parts of the world.

The measurement also helps to optimize engine operation, ensuring proper functioning of the exhaust after-treatment system.

Thoroughly tested

All NOx Sensor products match OE criteria and are calibrated and controlled at test facilities. Parts available for Cummins, DAF, Detroit, Freightliner, International, Iveco, Kenworth, MAN, Mercedes-Benz, Paccar, Peterbilt, Renault, Scania and Volvo. All products have a 1 year warranty.

Principle of operation

NOx sensor acts as oxygen sensor with extended functionality.

The sensing element is a ceramic chip (see Fig. 1) that consists of a heating circuit, small passage leading into two cavities, oxygen pumping circuit and NOx decomposition circuit.

NOx sensing element (chip)
Figure 1. NOx sensing element (chip)

Before operation, the ceramic chip is heated for approximately 1,5 minutes for it to become functional. As the exhaust gas enters the ceramic chip through the small passage (see Fig. 2), at the first cavity all the free oxygen molecules are pumped through the electrolyte and remaining gasses diffuse into the second cavity where NOx molecules are decomposed and the resulting oxygen measured as a small electric current. Additional circuit board (see Fig. 3) is used to convert the measured current to a signal which is compatible with the Engine Control Unit (ECU) communications protocol.

NOx sensing element in longitudinal section view
Figure 2. NOx sensing element in longitudinal section view

            Figure 3. Sensor circuit board

User Manual

The supply voltage of Dinex NOx sensors is limited within 9 – 36 Volts and the signal voltage ranges from 2.5 to 3.6 Volts. It is strictly prohibited to alter the arrangement of connector wires.

During storage or installation, please make sure that the sensor wires are hanging tension-free. After proper
installation the sensor wire should for a 180 degree loop to provide for safe play-distance (see Fig. 4).

It is likewise prohibited to wind or bend the wire (see Fig. 5).

Suggested wire handling during installation.
Figure 4. Suggested wire handling during installation.
 Inappropriate wire handling.
Figure 5. Inappropriate wire handling.

When installing the NOx sensor in non-specific (new) designations, please consider sensor locations carefully. It should not be placed overly close to bends, as the turbulence will disturb proper operation.

The installation angle should be up-right, considerable distance away from any bends (see Fig. 6).

Sensor placement suggestion.

         Figure 6. Sensor placement suggestion.

Sensor placement angles.
Figure 7. Sensor placement angles.

When choosing a location of a NOx sensor, please also consider the potential for pools of condensate water to form in the exhaust system. Some examples of this issue are illustrated in figures 8 and 9. The sensor location should be chosen such that during operation there is no risk for the condensate water to come in contact with the sensor head. Additional placement suggestions are given in figure 7.

Potential condensate pool in a silencer.
Figure 8. Potential condensate pool in a silencer.
Potential condensate pool in a vertical bend.

 Figure 9. Potential condensate pool in a vertical bend.

When replacing a NOx sensor please pay attention to its’ designation. The sensors that are located before the catalyst are regarded as “upstream”, but those that are located after the catalyst are considered as “downstream sensors”. The NOx concentration in both of these locations is very different so in some applications different sensors might be used for upstream and downstream locations. It is very important to avoid any mix-ups.

Please handle the product with care, do not use any spraying agents or chemicals to clean or paint them, do not attempt washing the sensor and its components with water or dismantling it. The use of such methods poses serious risk of failure (see Fig. 10).

Prohibited handling.

                     Figure 10. Prohibited handling.

Troubleshoot

Before replacing the old NOx sensor it is important to understand why it failed. Possible reasons for failures are listed below:

• Excessive soot/ash content in exhaust gas. The sensor head will be black (see figure 12).
• Contaminated exhaust gasses. Engine oil contamination is a common issue indicating worn out engine components.
• Lacking or excessive supply voltage due to short circuit, sudden voltage spikes or external power source.
• Direct contact with condensate during operation.

It is important to fix any of the listed issues before installing a new NOx sensor otherwise the risk of repeated damage remains. If the freshly installed sensor is not recognized or does not function, please use a multimeter to see if the power supply is within 9-36 Volts (12V nominal) at the sensor connector. Please also make sure that you follow any instructions regarding NOx sensor replacement issued by the manufacturer of your vehicle. If the sensor connects and is recognized but is showing signs of abnormal function, please make sure that the correct sensor is selected for its’ location (upstream or downstream – refer to user manual section).

Warranty

Please make sure that all the issues from troubleshoot section have been repaired before installing Dinex product. If evidence of any of the issues listed under troubleshoot section will be detected during warranty investigation, the claim will be rejected.

Damaged sensor thread and nut.

  Figure 11. Damaged sensor thread and nut.

Likewise, the sensor body and wiring must not bear visible signs of damage in order for the warranty to be valid. If the sensor thread or nut has sustained damage, it is evidence of excessive force that can potentially lead to failure (see Figure 11).

Evidence of excessive sootash.

  Figure 12. Evidence of excessive soot/ash.

If there are considerable stains of soot/ash on the sensor head (see Figure 12) it is evidence of a damaged DPF or poorly calibrated engine operation. The sensor chip in this case is easily damaged therefore warranty becomes void.

Damaged wire protector.

 Figure 13. Damaged wire protector.

Damaged wire protector is evidence of poor handling (see Figure 13) that can result in damaged wiring. In order for the warranty to be valid there must be no signs of wire damage.

Evidence of damaged wiring.

  Figure 14. Evidence of damaged wiring.

The area where wiring connects to the sensor head is most critical and prone to connection loss if treated poorly (see Figure 14). In case of damage, the warranty will not be valid.

Do not attempt to wash or submerge the sensor. Do not use any spraying agents. Store in dry environment only. If evidence of water will be found in the sensor head, or any chemical traces will be found on the product, the warranty will be void.