Remove the oxygen sensor and add excess hydrochloric acid with 5-10% ferric chloride solution. This ratio depends on the surface of the sensor head. Place the oxygen sensor in the solution and soak it. After 10-15 minutes, remove it and rinse it with water. Not only the surrounding four holes should be smooth, but the carrier inside is white after washing.
If the cleaning is not satisfactory, continue the work until you can see the white carrier.
After flushing with water, install the sensor and repeat the fourth step of the above measurement. Generally speaking, as long as it is not the sensor of the deputy factory, as long as the internal porcelain body does not burst, the heating resistor has no open circuit, and the oxygen sensor after the above cleaning can resume normal operation.