Air Filter

An engine's air filter keeps dirt and other debris from entering the engine, where it could potentially do damage. It's usually found inside in a plastic housing on one side of the engine. The size and shape of an air filter varies by vehicle, but all perform the same task.

Checking the Air Filter
Each vehicle is different when it comes to air filter housings, so check your owner's manual for instructions specific to your vehicle (some are much easier to check than others). However, the general procedure is the same.


  1. Have the engine OFF.

  2. Open the hood and locate the air filter housing.

  3. Unscrew, unclip, or remove the fasteners that hold the air cleaner housing together.

  4. Open the housing and remove the air filter.

Air filters.jpg

A clean air filter (left) compared to a dirty one (right).

Replacing the Air Filter
If the filter is dirty, replace it with a new one. You can purchase a replacement filter at a parts store or any other store that sells automotive supplies. Installation is the same as removal, just in reverse.


  • A dirty or clogged air filter can lead to poor performance and reduced fuel economy.


  • On some vehicles, the powertrain control module (PCM, the engine computer) is inside the air cleaner housing and is cooled by the air going through it. A very clogged air filter can cause a reduction in airflow, which can cause the PCM to overheat and possibly fail.


How Often it Needs Service

Even if your air filter isn't very dirty, a number of manufacturers recommend replacing them at regular intervals (such as every 2 years or 3,000 miles). This is because air filters can pick up dust and pollen so fine that it may not be easy to see.


Get Your Vehicle Serviced if You Notice:

  • Poor performance

  • Reduced fuel economy

Cabin Filter

Quite a few vehicles also have a cabin air filter, which filters dust and pollen out of the air that comes into the passenger compartment. This
filter is often located behind the glove box, but
may be elsewhere. Just like with an air filter, a cabin filter will need to be changed if it gets dirty. 


Checking the Cabin Filter
Each vehicle is a bit different when it comes to cabin filter removal, but quite often the glove box has to be unclipped and lowered to gain access. Your owner's manual will list the location of your vehicle's cabin filter, if it has one.


What Happens if the Cabin Filter is Dirty

A clogged cabin filter can lead to reduced
airflow out of the vents, which can make the A/C or heat seem to work poorly.  Dirty cabin filters can also lead to unusual odors.

Replacing the Cabin Filter
Typically, cabin filters are only sold at dedicated parts stores. Installation is the reverse of removal, but make sure you check the position of the old one before you take it out. There will be an arrow on it that points in the direction of airflow (either up or down), and when you install the new one you want the arrow to be pointing in the same direction as it was on the old one.

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A dirty cabin filter (left) compared to a new one (right).

Where Can I Learn the Exact Procedure?

The internet is a great resource if you want to learn how to check your air or cabin filter. If you're a visual learner, definitely check out YouTube for instructional videos. For example, search for "2005 Prius cabin filter" or "2010 Malibu air filter". We can also show you how to check your vehicle's filters at your next oil change.