for private car owners, how often will the air filter of their car be replaced or cleaned, which will help car maintenance? this is the basic knowledge of car owners maintenance. what happens if it is replaced irregularly? as a person who has been in the auto parts industry for many years, he is often asked about the timing of filter replacement. here is a brief summary of the relevant issues about the air filter replacement cycle. i hope it will be helpful to everyone. . the main function of the air filter is to filter impurities in the air and provide clean gas for the engine to do work. in this process, the impurities in the air are adsorbed on the air filter surface. after reaching a certain mileage, the above picture will be formed. (black) as shown, the filtering effect at this time is already very poor and must be replaced in time. in addition, when you find that the car is weak, the sound of the engine is dull, and the fuel is consuming, you should replace the air filter in time.