What Is an Engine Air FIlter? Here's What You Should Know

What Is an Engine Air FIlter? Here's What You Should Know

19th Mar 2019

hand holding car air filter

Understand Air Filters

Contrary to what some people believe, cars don't contain just one air filter. Rather, most modern cars have two air filters: one for the cabin air and another for the engine air. The cabin air filter is designed to remove dirt, dust and other impurities from the air as it enters your car's cabin, allowing you and your passengers to breathe a little more clearly. So, what's the purpose of the engine air filter?

Engine Air Filter Explained

Typically found between the air resonator box and your car's engine, the engine air filter is a paper or metal filter that's designed to remove dirt, dust and other impurities from the air as it enters the engine's combustion chamber. Air flows into the resonator box before entering a separate compartment, known as an air intake box, in which a filter is housed. As the air flows through the filter, the filter catches micro-sized particulate matter, preventing those impurities from entering your engine's combustion chamber.

All combustion gas engines need three things to function: fuel, spark and air. Fuel is fed to the engine via a fuel pump that pulls it from your car's tank. Spark is generated by the spark plugs residing in the cylinder head. And air is provided by the air resonator and intake boxes, the latter of which contains a filter to clean the air before it enters your engine's combustion chamber.

Signs You Need to Change Your Engine Air Filter

It's recommended that you replace your car's engine filter according to your owner's manual. Depending on the type of car you drive, the manufacturer may recommend changing your engine air filter every 20,000 to 50,000 miles under normal driving conditions. If you frequently drive on dirt roads or other areas with high levels of airborne particulate matter, though, you should change your engine air filter more frequently.

If your car's engine air filter is overdue for changing, you may notice some of the following symptoms:

  • Poor gas mileage
  • Check engine light (CEL)
  • Engine misfiring
  • Black exhaust smoke
  • Lower horsepower
  • Strong odor of gasoline
  • Failing catalytic converter

If you discover any of these symptoms, consider replacing your car's engine air filter. It's an inexpensive component that most drivers can replace themselves. Of course, you can also take your car to a professional mechanic to have the engine air filter changed. Either way, it's important to maintain a clean engine air filter so that dirt, dust and other impurities don't make their way into your engine's combustion chamber.

vehicle air filter graphic