What's the Point of the Air Filter in My Car?

Air Filter

Considered a part of the fuel supply system in a vehicle, a vehicle air filter helps to keep the engine clean and free of debris. Having a mechanic change out the air filter on a regular basis helps keep the vehicle operating in top condition. Additionally, not only does a properly working air filter keep the air for the combustion process clean, a clean filter helps improve a vehicle's overall gas mileage.

The role of the air filter

The role of the air filter in a vehicle is to filter the air as it enters through the throttle body via the ductwork, on newer vehicles, or through the carburetor, on older models. The air passes through a paper, foam, or cotton filter before entering the combustion chambers through the intake manifold. The filter helps remove dirt, insects, and other particles from the incoming air, keeping such debris out of the engine.

Without an air filter, the engine would become clogged with debris, such as dirt, leaves, and insects, soon becoming obstructed completely and eventually breaking down altogether. Vehicle owners can find the air filter either in the round air cleaner atop the carburetor in older vehicles or the cold air collector box, located to one side of the engine in newer vehicles.

Signs that an air filter needs changing

Vehicle owners should learn to recognize some obvious signs that they need to change their air filter. If they think it is time to change it, they should check with a mechanic who can let them know for sure. Some of the more common signals that it is time to change a vehicle’s air filter include:

  • A noticeable decrease in gas mileage

  • Fouled spark plugs, which cause ignition problems, such as a rough idle, engine misses, and starting problems

  • The Check Engine Light comes on, caused by the increase in engine deposits due to a too-rich fuel mixture

  • Decreased acceleration due, in part, to the restricted air flow caused by a dirty air filter

  • Strange engine noises due to the lack of air flow from a dirty filter

The frequency that vehicle owners need to change out the air filter in their vehicle depends largely on environmental conditions, how hard they drive the vehicle, and how often they drive the vehicle. The best way to know when to change the air filter is to check with a mechanic, who can also offer advice about the best air filter for a vehicle.

When should you change an air filter?

You can have a mechanic change out the air filter in your vehicle on a variety of different schedules. Most often, a mechanic will inspect the filter while changing the oil in your vehicle and change it when it reaches a certain level of contamination. Some other schedules include changing the filter every other oil change, every year, or based on the mileage driven. Regardless of the schedule followed, if the vehicle exhibits any of the above signs, you should have the mechanic check the air filter on your next visit.

Other types of vehicle air filters

In addition to the intake air filter, some vehicles, especially older models, also use a cabin air filter. Like the intake air filter, the cabin air filter (which is usually located behind or around the glove compartment) removes all the dirt and debris from the air.

Instead of cleaning the air for use by the engine, a cabin air filter cleans the air before it enters the passenger compartment of the vehicle. Check with a mechanic to see if your vehicle contains a cabin air filter and if it needs to be replaced.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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