What does it mean when the engine yellow light is on in a car?

[VanWeston]

When the engine yellow light is on in a car, it indicates an engine malfunction. Possible causes include: Oxygen sensor failure: If the oxygen sensor is damaged or the sensor connector is damaged or loose, it can cause the air-fuel mixture to be too lean or too rich, triggering the warning light. Poor fuel quality: Substandard fuel, often from filling up at non-standard gas stations with low-quality gasoline, can lead to incomplete combustion of the air-fuel mixture during engine operation, causing the yellow light to illuminate. Spark plug carbon buildup: Excessive carbon deposits can cause the ignition coil to reverse breakdown, leading to ignition coil failure, poor ignition, and incomplete combustion, which will also trigger the warning light. Engine misfire: An engine misfire may also be accompanied by the following symptoms: increased fuel consumption, black smoke emission, lack of power during acceleration, severe shaking, and increased noise, at which point the warning light will also come on.