What does it mean when the engine fault light comes on in the car?

[LeDante]

Here are the possible reasons why the car displays an engine fault: 1. Poor fuel quality: Low-quality fuel causes incomplete combustion of the air-fuel mixture, failing to meet the engine's fuel performance requirements, which triggers the engine fault light. 2. Oxygen sensor malfunction: A damaged oxygen sensor or a faulty/loose sensor connector can lead to an excessively lean or rich air-fuel mixture, causing the fault light to illuminate. 3. Mass airflow sensor failure: If the mass airflow sensor or its wiring malfunctions, the ECU cannot receive the correct intake air signal, resulting in improper fuel control. This leads to an excessively lean or rich mixture, causing symptoms such as rough idling, poor acceleration, increased fuel consumption, and black smoke from the exhaust pipe, ultimately affecting the car's engine performance.