How often should an engine air filter be changed?

Updated: March 02, 2020
The air that enters your engine flows through the air filter. The filter catches sand and other debris protecting your engine and helping it last longer. The engine air filter should be replaced between 15,000 and 30,000 miles, depending on driving conditions.
Engine air filter in a carReplacing an air filter.
If you have a turbocharged engine or often drive on unpaved roads, it needs to be changed more often. If you don't drive a lot, an air filter should be replaced at least every 3 years, as with age it becomes brittle. An old filter can tear, allowing dirt and sand to enter the engine.

An air filter is installed inside the air filter box. It's made of pleated paper-like material. The air flows from the bottom up, so the dirt and larger objects are trapped in the box under the filter.

As the air filter gets dirty and gradually clogs up, it restricts the air flow into the engine. This adds strain to your engine, making it harder for it to "breathe." Due to increased vacuum, some dirt particles could be sucked through the filter and scratch the engine pistons and cylinder walls. For the same reason, the engine may start consuming more oil.
Symptoms of a dirty air filter include a lack of power on hard acceleration and at higher RPMs, although it's not always noticeable.
Dirty vs clean engine air filterClean versus dirty air filter. See more illustrations: Fig1. Fig2.
The fuel economy may also be affected, although not by much. In extreme cases, the "Check Engine" warning light may illuminate on the dash.

The air filter is inspected during your regular oil changes. Your mechanic can check its condition and let you know if it needs to be replaced. It the filter looks clean, leave it; if it's very dirty, change it. Anything in between is a judgement call. Some mechanics test the condition of the air filter by looking through it at the light source; if no light is visible through the filter, it must be replaced.
Engine air filter in a car The filter on the right is dirty after 24,000 miles.
For example, compare these two air filters in the photo below. The filter on the right was changed one year ago, but the owner of this Honda drives over 24,000 miles a year. Now it does look dirty, so the owner decided to replace it again.

If you want to check it yourself, your vehicle's owner's manual has the engine compartment map. In some cars, to open an air filter box you will need some tools, like an 8-mm or 10-mm socket or a screwdriver. In other cars, the air filter box cover is held by a few clips. In most cars, it's not a very difficult job. Whenever an air filter is replaced, it's a good idea to clean any debris that may have accumulated inside the air filter box.
If you change your air filter yourself, make sure it fits properly and the air box is closed tight after the job is done. If the air filter box is not closed properly, the Check Engine light may come on.

Replacing an air filter in the repair shop is not very expensive: $10-$30 labor plus $19-$45 part.
Is it important to have an air filter replaced at a dealer or can a fast lube shop do the job? Replacing an air filter is fairly easy in most cars and can be done in any repair shop, however using a factory (OEM) part from a dealer will ensure that it fits properly. If you opt for an aftermarket part, invest a little extra for a premium brand for better engine protection.

Are washable air filters better? You will find as many arguments for using them as you will against them. If it's a high quality filter and is installed properly and cleaned regularly, it will work. However, we have seen problems related to washable filters or their installation. We also know cases where having a washable air filter created issues with the warranty coverage. Considering this, we recommend doing some research before and keeping the OEM filter and hardware if you do install a washable filter. The air filter is not an expensive part, but it does a very important job protecting the engine.

Is it necessary to replace a cabin (pollen) filter whenever an engine air filter is replaced? It's not necessary, however if the engine air filter is dirty, the cabin filter is likely to be in the same condition.