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Analysis of common failures of automobile oxygen sensors

  • Time of issue:2021-02-25 13:59

Analysis of common failures of automobile oxygen sensors

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  • Time of issue:2021-02-25 13:59
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1. Oxygen sensor poisoning

Oxygen sensor poisoning is a fault that often occurs and is difficult to prevent, especially for cars that often use leaded gasoline. Even a new oxygen sensor can only work for a few thousand kilometers. If it is only a slight lead poisoning, then using a box of unleaded gasoline can eliminate the lead on the surface of the oxygen sensor and restore it to normal operation. But often due to the excessively high exhaust temperature, lead invades its interior, which hinders the diffusion of oxygen ions and makes the oxygen sensor ineffective. At this time, it can only be replaced.

In addition, silicon poisoning of oxygen sensors is also common. Generally speaking, the silicon dioxide generated by the combustion of silicon compounds contained in gasoline and lubricating oil, and the organic silicon gas emitted from improper use of silicone rubber gaskets will cause the oxygen sensor to fail. Therefore, use good quality fuel and lubricating oil. . When repairing, choose and install rubber gaskets correctly, and do not apply solvents and anti-sticking agents other than those specified by the manufacturer on the sensor.

2. Carbon deposition

Due to poor engine combustion, carbon deposits on the surface of the oxygen sensor, or deposits such as oil or dust inside the oxygen sensor, will hinder or block the outside air from entering the oxygen sensor, causing the oxygen sensor to output signals inaccurately and the ECU cannot be timely Correct the air-fuel ratio. Carbon deposition is mainly manifested by the increase in fuel consumption and a significant increase in emission concentration. At this time, if the sediment is removed, normal operation will resume.

3. Oxygen sensor ceramic is broken

The ceramic of the oxygen sensor is hard and brittle. It may be broken and become invalid if it is hit with a hard object or blown with a strong airflow. Therefore, be especially careful when handling, and replace it in time if there is a problem.

4. The heater resistance wire is blown

For the heating type oxygen sensor, if the heater resistance wire is ablated, it is difficult to make the sensor reach the normal working temperature and lose its function.

5. Check the appearance and color of the oxygen sensor

Remove the oxygen sensor from the exhaust pipe and check whether the vent hole on the sensor housing is blocked or the ceramic core is damaged. If damaged, the oxygen sensor should be replaced.

The main oxygen sensor includes a hot rod that heats the zirconia element. The heating rod is controlled by the (ECU) computer. When the air intake is small (low exhaust temperature), the current flows to the heating rod to heat the sensor to enable accurate detection of oxygen concentration. Platinum electrodes are installed on the inner and outer sides of the zirconium element (ZRO2) in the test tube state. In order to protect the platinum electrodes, the outer side of the motor is covered with ceramics. The oxygen concentration on the inner side is higher than the atmosphere, and the oxygen concentration on the outer side is lower than that of the car exhaust gas. . It should be pointed out that after the three-way catalytic converter is used, unleaded gasoline must be used, otherwise the three-way catalytic converter and oxygen sensor will quickly fail. Note again that the oxygen sensor plays an important role in stabilizing the throttle and preparing standard mixing. When frequent enrichment or lean mixing, the (ECU) computer will ignore the oxygen sensor information and the oxygen sensor will not work.

Rear oxygen sensor

Today vehicles are equipped with two oxygen sensors, one at the front and one at the rear of the three-way catalytic converter. The function of the front is to detect the air-fuel ratio of the engine under different working conditions, and the computer adjusts the fuel injection amount and calculates the ignition time according to the signal. The main thing at the rear is to check the working quality of the three-way catalytic converter! That is the conversion rate of the catalyst. An important basis for detecting whether the three-way catalytic converter is working properly (good or bad) by comparing with the data of the front oxygen sensor.



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