1. Oxygen sensor poisoning
Oxygen sensor poisoning is a common and difficult to prevent malfunction, especially in cars that frequently use leaded gasoline. Even new oxygen sensors can only operate for thousands of kilometers. If it is only a mild lead poisoning, then using a box of unleaded gasoline can eliminate the lead on the surface of the oxygen sensor and restore its normal operation. But often due to the high exhaust temperature, lead enters its interior, hindering the diffusion of oxygen ions and rendering the oxygen sensor ineffective. At this point, it can only be replaced.
In addition, silicon poisoning in oxygen sensors is also a common occurrence. Generally speaking, the silicon dioxide generated by the combustion of silicon compounds in gasoline and lubricating oil, as well as the organic silicon gas emitted by improper use of silicone rubber sealing gaskets, can cause the failure of oxygen sensors. Therefore, high-quality fuel and lubricating oil should be used. When repairing, it is necessary to correctly select and install rubber gaskets, and do not apply solvents and anti adhesive agents other than those specified by the manufacturer to the sensor.
2. Carbon deposition
Due to poor combustion of the engine, carbon deposits may form on the surface of the oxygen sensor, or deposits such as oil or dust may enter the interior of the oxygen sensor, which can hinder or block the entry of external air into the sensor, causing the output signal of the oxygen sensor to be inaccurate, and the ECU cannot timely correct the air-fuel ratio. Carbon deposition is mainly manifested as an increase in fuel consumption and a significant increase in emission concentration. At this point, if the sediment is removed, normal operation will be restored.
3. Oxygen sensor ceramic fracture
The ceramic of the oxygen sensor is hard and brittle, and it may shatter and fail when struck by a hard object or blown by strong airflow. Therefore, special care should be taken when handling and problems should be promptly replaced.