The fault can also be judged by observing the color of the top part of the oxygen sensor
The top part is light gray, which is the normal color of the oxygen sensor.
The top part is white, caused by silicon pollution, at this time the oxygen sensor must be replaced.
The top part is brown, and it is caused by lead pollution. If it is serious, the oxygen sensor must be replaced.
The top part is black top, which is caused by carbon deposit. After removing the engine carbon deposit fault, the carbon deposit on the oxygen sensor can generally be automatically removed.