What does an air filter do in a car?

You actually have two types of air filters in your car: one that cleans the air for you and one that cleans the air for your engine.

The cabin air filter’s job is to make sure the air you’re breathing in the cockpit is clean. It prevents pollutants such as dust, smog, pollen, mold spores, leaves, rodent droppings, and other unwanted debris from being blown into your face. If you have a dirty cabin air filter, getting it replaced is literally a breath of fresh air!

The engine air filter has the important job of preventing dust, dirt, and other debris from getting into your engine, while also ensuring your engine is getting the correct mixture of air and fuel. When you press your gas pedal, you’re controlling how much air and fuel are allowed into your vehicle’s engine, kind of like controlling its breathing pattern of inhale and exhale. If the engine air filter becomes restricted, the limited airflow leads to poor performance, weak acceleration, increased fuel consumption, and even oil leaks. And you don’t have to be a doctor to know that’s not good.

What are the signs you need an air filter replacement?

Cabin and engine air filters show their wear in different ways. Here’s what to watch for:

• Cabin air filter symptoms - Dirty, musty, or smelly air inside the car, visible dirty particles in the airflow, or heating and A/C that don’t seem to work as well as before.

• Engine air filter symptoms - Reduced gas mileage, loss of power, strange engine noises, frequent misfires, or the dreaded “check engine” light. A severely clogged filter can even make the car hesitate when you accelerate.

If you’re noticing these signs, it’s a good idea to get your filters checked before the problems get worse.

Why is air filter replacement important?

Air filters may seem small, but they protect some of the most critical systems in your vehicle. A clean cabin filter keeps allergens, dust, and even mold spores from circulating through your vents. For drivers with allergies or asthma, that clean air makes a big difference.

On the engine side, a clean filter guarantees the right balance of air and fuel. That means smoother acceleration, more efficient combustion, and less strain on your engine. Running with a clogged filter is like trying to jog while breathing through a straw - eventually, performance suffers and other systems take on stress they weren’t designed for.

How often should you replace your car’s air filters?

Over time, both filters get dirty and need to be replaced. Replacement schedules vary depending on the make and model, driving conditions, and manufacturer recommendations. An air filter’s replacement timeline typically ranges between 15,000-40,000 miles.

If you’re often in stop-and-go traffic, drive on dusty or unpaved roads, or live in areas with heavy pollen, you may need replacements more often. Cabin filters can usually be inspected by eye, and an engine filter is easy for a tech to check during routine service.

Has it been a while since you’ve had your filters looked at? It never hurts to have an expert check next time you’re in the shop.