Mechanics say replacing your car’s dirty cabin air filter can improve the air quality in your car. When it comes to keeping up with general vehicle maintenance, replacing the cabin air filter probably isn’t at the top of your list. Heck, it may not even be on your list.

Cabin air filters often live in the shadows of their more popular cousins — the engine air filter and oil filter — and some drivers don’t even know they exist. But highly rated auto technicians say they play an important role in filtering pollutants from entering the vehicle’s cabin.

“The cabin air filter is kind of out of sight, out of mind,” says Tom Potter, owner of highly rated Japanese Auto Masters in Virginia Beach, Va. “If you tell someone they need their cabin air filter changed, some say, ‘What is that?’ They think you’re talking about the engine air filter. I’ve seen people go 90,000 miles without changing it because they didn’t know they needed to.”
Your car’s engine air filter should be replaced when it gets dusty or dirty enough. But don’t let a mechanic convince you to replace it too frequently.

The primary purpose of cabin air filters, located on most vehicles since 2000, is keeping the air inside your vehicle’s cabin clean.
It’s typically located behind the glove compartment or under the hood or dashboard on most modern vehicles. Its job is to filter all of the air that comes through the car’s HVAC system to prevent pollutants, such as dust, pollen, smog and mold spores from entering. The filters can also catch rodent droppings, leaves, and other unwanted debris.

“They help with allergy problems,” says Potter, who has a monthly contest at his shop to pick the dirtiest cabin filter (the winner gets a free oil change.) “It helps prevent pollen from getting in the car if you live in an area with a lot of trees.”
Besides improving air quality, replacing the cabin air filter may prevent an expensive repair. “When the air is dirty, the A/C will work harder and the motor can burn up,” says Troy Roberts, owner of highly rated CarePair.