What are the reasons for the failure of the nox nitrogen oxygen sensor?

Wed May 25 2022 Yan Xia

The main reasons for exceeding the standard of nitrogen and oxygen in automobile exhaust are poor intake system, carbon deposition in the engine, cylinder wear, failure of the three-way catalytic converter, and loss of control of the nox nitrogen and oxygen sensor. Different governance methods should be used according to the reasons for exceeding the standard. (The condition is that the engine control computer should be checked first)


1. First check whether the engine is normal
A simple inspection can be done. The engine is the heart of the car. To check whether the engine is normal, you can remove the spark plug to see if there is oil and it is clean. It means that the ignition is normal and the engine is not oily. Increase the throttle to observe whether the operation is stable and powerful. If the above inspection No problem is normal.
2. The three systems of the vehicle are too dirty
This situation usually occurs when the vehicle is relatively new, but the test result exceeds the standard, or the exceeding standard is not serious and only exceeds a few percent or a few tenths. This situation shows that the exhaust gas treatment system of our vehicle is three-way catalytic converter. There is no major problem with the engine and oxygen sensor, and the cause of the exhaust gas exceeding the standard is mostly because the three systems of the vehicle (intake system, exhaust system, fuel system) are too dirty.
Solution
Change the high-grade oil and pull the high-speed (slightly exceeding the standard can not change the oil or add fuel additives and pull the high-speed, and the most appropriate method is to change the high-grade gasoline and add the additives and then pull the high-speed) High-speed cleaning of the engine oil circuit and Cylinders play a considerable role. The reason is that when the engine is running at high speed, the fuel supply increases and the fuel flow rate also increases, which helps to flush out the dirt and impurities in the oil circuit to achieve the cleaning effect.
3. Three-way catalytic converter poisoning
Three-way catalytic converter poisoning is the most important reason for automobile exhaust gas exceeding the standard. Three-way catalytic converter is the most important external purification device installed in automobile exhaust system. It can remove harmful gases such as CO, HC and NOx from automobile exhaust gas. Converted to harmless carbon dioxide, water and nitrogen by oxidation and reduction. Because this catalyst can convert the main harmful substances in the exhaust gas into harmless substances at the same time, it is called ternary.
Solution
Once the three-way catalytic converter is poisoned, as long as the three-way catalytic converter has not lost its activity and is not completely blocked, cleaning the three-way catalytic converter can restore the activity of the three-way catalytic converter, and the most thorough solution is to replace the new three-way catalytic converter. Metacatalyst.
However, the original new three-way catalytic converter is expensive because it contains precious metals, and of course the price is not cheap, but most of the three-way catalytic converter products on the market are from auxiliary factories. Although the price is slightly cheaper than the original one, the quality of the manufacturing process is high. Neither can be guaranteed, and often only the old ones are recycled and refurbished or fail to meet the production requirements. Therefore, it is recommended that riders choose the original one to buy a new three-way catalytic converter.
4. Nox nitrogen oxygen sensor is damaged
Excessive exhaust gas is not necessarily the poisoning of the three-way catalytic converter. The damage of the oxygen sensor is also an important and easily overlooked reason. In the engine that uses the three-way catalytic converter to reduce exhaust pollution, the nox nitrogen oxygen sensor is essential. element.
Since the air-fuel ratio of the mixture deviates from the theoretical air combustion ratio, the purification ability of the three-way catalyst for CO, HC and NOx will drop sharply, so a nox nitrogen oxygen sensor is installed in the exhaust pipe to detect the oxygen concentration in the exhaust gas , and send a feedback signal to the ECU, and then the ECU controls the increase or decrease of the fuel injection amount of the injector, so as to control the air-fuel ratio of the mixture near the theoretical value.
Solution
Generally, if the oxygen sensor is damaged, it will be replaced directly. The price is not very expensive. Generally, it is about a few hundred yuan. However, some unpopular cars or high-end cars are more expensive because they are difficult to obtain. If it is damaged, the fuel consumption will increase significantly, so replacing the bad oxygen sensor has a non-negligible effect on the fuel economy of the vehicle.

What are the reasons for the failure of the nox nitrogen oxygen sensor?