Why does the oxygen sensor fault code keep reappearing after being cleared?

[McBenjamin]

The reasons why the oxygen sensor fault code keeps reappearing after being cleared are as follows: If the fuel from the gas station is substandard, containing excessive lead and silicon compounds, it can cause poisoning and damage to the oxygen sensor and even the catalytic converter. When the oxygen sensor first shows a fault code, it is only surface poisoning and still relatively mild. If high-quality fuel is used at this point, the toxic substances on the surface can be eliminated, restoring the oxygen sensor to normal operation. Extension: The function of the oxygen sensor is to detect the oxygen content in the exhaust. If there is too much oxygen, it indicates that the air intake is excessive while the fuel injection is insufficient, leaving unused oxygen, which prompts the system to increase fuel injection. If the oxygen content is too low, it means the fuel injection is excessive, and there isn't enough oxygen, leading the system to reduce fuel injection. Therefore, the oxygen sensor is a crucial component for fuel trim, constantly fine-tuning the air-fuel ratio to the optimal state.