Why is the engine yellow light on?

[VonAlejandro]

There are two scenarios when the engine yellow light on the car dashboard illuminates: 1. When the car's power is turned on, the vehicle undergoes a self-check. During this time, not only the engine yellow light but also other warning lights will illuminate simultaneously before turning off, which is a normal phenomenon. 2. If the engine fault yellow light remains on after starting the car, this indicates that the ECU is alerting you to an engine fault, which is abnormal. During normal vehicle operation, the illumination of the yellow warning light is most likely caused by three reasons: 1. Oxygen sensor malfunction. 2. Cold winter weather. 3. Poor fuel quality. The engine fault light is also known as the engine exhaust emission check light, so when this light is on, it could also indicate excessive exhaust emissions.