What is the reason why the car engine fault light is on? It's not always open, but it will be open for a day or two.

The failure lights of general vehicles are mostly caused by the fuel discharge system. Start and stop the vehicle when the fault light is on. After starting the vehicle three times, observe whether the fault light is still on. If it is still on, you need to go to the store to check the fault code in time to see if it is an engine fault or a sensor fault. Otherwise, it may be an accidental failure, and it is not necessary to go to the store for inspection in time.

Extended data:

The reason why the fault light of automobile engine is always on;

1. When the cold car starts, especially when the weather temperature drops sharply, the pollution lamp will light up because of the temperature correction problem of the computer, but as long as the temperature drops to a certain extent and there is no fluctuation, it will be relatively stable.

2. Some sensor computer boards have failed, which led to the pollution of lamps.

3. Poor gasoline quality will lead to insufficient combustion of the mixture in the cylinder, which will lead to pollution of the lamp and easy carbon deposition.

4. If the mileage of the engine is too long, the working characteristics of the spark plug will be weakened, leading to the lighting of the pollution lamp.

5. Excessive vehicle age and mechanical aging lead to poor engine working conditions, poor combustion and ignition, and light pollution.

6. Too much carbon deposit makes ignition difficult, which will lead to reverse breakdown of the ignition coil, resulting in poor ignition and incomplete combustion, which will pollute the lamp. A notable feature of this phenomenon is that when the ignition coil fails, the engine always shakes violently. If it is not shaken violently all the time, the ignition coil can be basically eliminated.

7. The existence of carbon deposits at the air inlet and piston top will lead to poor atomization, resulting in insufficient combustion and pollution of lights.

8. There are many reasons for light pollution, but the first three are the most. Special note: When the pollution light is on, the engine will not shake or slightly shake. At this point, the owner does not need to worry when using it, and can use it normally. Sometimes he can check or maintain it at his convenience.

Source: Baidu Encyclopedia-Engine