How to judge whether the air filter needs to be replaced? What are the obvious signs?

As an important part of the car engine intake system, the air filter is responsible for filtering impurities in the air and protecting the engine from dust and particulate matter. However, as time goes by and the vehicle's use conditions change, the air filter will gradually become clogged and lose its filtering efficiency, which will not only affect the performance of the engine, but may also cause more serious mechanical failures. Therefore, regular inspection and timely replacement of the air filter is a key step in maintaining vehicle health and extending engine life. So, how to judge whether the air filter needs to be replaced? What are the obvious signs?

1. Observe the appearance of the air filter
The most direct way is to regularly check the appearance of the air filter. A brand new air filter is usually white or light gray, and the paper structure is tight and uniform. As the use time increases, the filter will gradually accumulate dust and impurities, the color will become darker, and even oil stains may appear. If the surface of the filter is covered with a thick layer of dust or there are obvious oil stains, it means that it has approached or reached the critical point of replacement.

2. Check engine performance changes
The blockage of the air filter will directly affect the engine's intake efficiency, resulting in reduced power, weak acceleration, and increased fuel consumption. If you find that the vehicle is more "laborious" than before during normal driving, especially when accelerating or climbing, this may mean that the air filter has restricted the intake volume and needs to be replaced.

3. Pay attention to abnormal sounds
When the air filter is severely blocked, the engine may make abnormal sounds such as "hissing" or "buzzing" when running, which is because the air flow is turbulent due to poor intake. Although this sound may be related to other faults, if you also notice the performance degradation mentioned above, then the problem with the air filter is more suspicious.

4. Use professional testing tools
For more accurate judgment, some professional repair shops will use airflow meters or pressure gauges to test the air permeability of the air filter. This method can quantify the degree of blockage of the filter and give more scientific replacement suggestions. Although this requires certain professional equipment and knowledge, it is a reliable way to ensure the accurate status of the air filter.