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. 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 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.
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. Many mechanics test the condition of the air filter by looking at the light source through the filter. If no light is visible through the filter, it must be replaced.
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.