What are the symptoms of a faulty front oxygen sensor?

[TylerLee]

Symptoms of a faulty front oxygen sensor: 1. Increased fuel consumption, as carbon buildup on the oxygen sensor can cause abnormal signal output, leading to an imbalance in the engine's air-fuel mixture ratio and resulting in higher fuel consumption; 2. Increased pollutant emissions, failing the annual vehicle inspection's tailpipe emissions test due to the oxygen sensor malfunction, as the three-way catalytic converter's purification capability is limited, and improper oxygen sensor operation can cause incomplete combustion, increasing pollutants; 3. Potential black smoke emission, caused by an abnormal air-fuel ratio due to the oxygen sensor malfunction; 4. Unstable engine speed and shaking, also due to an abnormal air-fuel ratio.