A particle as small as a grain of salt can pass through a damaged air filter and cause a lot of damage to internal engine parts, such as cylinders and pistons, which can be very costly to repair. That's why it's so important to replace your air filter regularly. The frequency with which the engine air filter will need to be replaced varies. Maintenance schedules for different vehicle brands differ in how often the air filter needs to be changed.
On most Chevrolet engines, for example, the recommended change interval is every 45,000 miles, but Ford says it should be done every 30,000 miles on many of its engines. Hyundai also says every 30,000 miles, but shortens it to 15,000 for “severe driving conditions, including heavy traffic in hot climates and frequent driving on unpaved roads or dusty conditions. These rules will apply to other brands as well. If you are driving in such conditions, it will often be necessary to replace the air filter first.
A good rule of thumb is to inspect your air filter (or ask a mechanic to do it for you) at least once a year. If the filter is covered with dirt or is full of insects, leaves, or other debris, it's time to use a new one. If there is only a little dirt on the surface or only in one area, it's probably good to go longer. Try brushing dirt off the surface and turning the filter 180 degrees to expose the cleaned area to the main airflow.
The cabin air filter is usually located under the dashboard and behind the glove compartment, and air passing through it enters through the base of the windshield and bypasses the engine. As a general rule, most average drivers should be able to go a year or two before needing a new air filter. The good news is that replacing your car's cabin air filter is even easier and cheaper than changing your engine air filter. If you've recently noticed that you need to refill your gas tank more often than usual, it's probably time to check your air filter.
One of the most common problems you'll encounter when you need to change your engine's air filter is decreased fuel consumption. A dirty engine air filter will usually look dirty with dirt, dust, or stains visible within the folds. If venting the folds of the air filter by hand causes dirt to fly away and leaves the hand dirty, the filter must be replaced. Like vehicle air filters, cabin air filters should also be changed regularly as part of routine vehicle maintenance.
A Department of Energy study found that the electronic engine controls of modern vehicles are “sophisticated enough to prevent a clogged air filter from affecting the vehicle's fuel economy. However, engines rely on clean, good airflow to produce power and rapid acceleration, so restricting the amount of air will definitely affect performance. The purpose of the engine air filter is to prevent dust, dirt, and other environmental contaminants from entering the engine. In most cars, the cabin air filter is usually placed behind the glove compartment or under the dashboard.
When you take your car for regular maintenance, the mechanic will most likely inspect the engine air filter for dirt. To locate the engine air cleaner housing, look for a large plastic housing, usually black, that sits above or to one side of the engine.