Why is there no fault code when the throttle duty ratio is negative?

The following are the functions of the throttle:

1. The function of the automobile throttle is to adjust the air to enter a controllable valve of the engine, and then enter the intake pipe (different cars, different design mixing places) and then mix with gasoline to form a combustible mixture, which will participate in combustion and do work. One of the processes of providing power for vehicles;

2. Throttle is the most important component in the EFI automobile engine system. Its upper part is the air filter, and the lower part is the engine block, which is the throat of the automobile engine and regulates the speed of the vehicle.

3. Whether the car accelerates flexibly is closely related to the cleanliness of the throttle. The owner adjusts the throttle opening by stepping on the throttle to slow down when he arrives.