1. Reduction in fuel mileage
One of the first symptoms that an air filter may need replacing is a reduction in fuel mileage. A filter that is highly contaminated with dirt and debris will not be able to filter the air efficiently, and the engine will receive less air as a result. This will reduce the efficiency of the engine and will cause it to use more fuel to move the same distance or speed as would otherwise be required with a clean filter.
2. Decreased engine performance
Another symptom of a dirty air filter is a reduction in engine performance and power. The reduced air intake from a dirty filter will negatively impact the efficiency of the engine. In severe cases, such as with a clogged air filter, the engine may experience a significant reduction in acceleration and total power output.
3. Dirty air filter
The best way to know if an air filter needs to be replaced is by simply taking a look at it. If, when the filter is removed, it appears to be significantly covered in dirt and debris on the intake side, then the filter should be replaced.
Usually, checking the air filter is a relatively simple procedure that can be done on one’s own. But if you do not feel comfortable doing such a task, or it is not a simple procedure (as in some case with European vehicles), have it checked by a professional technician, such as one from YourMechanic. If needed, they will be able to replace your air filter and restore proper performance and fuel efficiency to your vehicle.