Why doesn't the engine self-test fault light come on?

It is normal that the engine self-test fault light does not light up, because the fault light will light up when the car is not started, and will automatically go out after 3-5 seconds.

When the engine fails, these failures will produce a series of codes, which will appear on the dashboard in the form of indicator lights after ECU reads the fault codes. If the engine self-test light continues to light up after the car is started, it means that the engine may be faulty.

Extended data:

If it is on all the time during driving, it is mostly because there is something wrong with the engine, usually because there is too much carbon on the throttle or the engine, or because the mixer is out of proportion after the oxygen sensor fails.

Engine fault lights are usually caused by the fuel discharge system. Start and stop the vehicle when the fault light is on. After starting and stopping the vehicle three times, observe whether the fault light is still on when starting the vehicle. 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 problem or a sensor failure. Otherwise, it may be an accidental failure, and it is not necessary to go to the store for inspection in time.