Cars can have one or two air filters. One is for your engine and new models have one for your breathing air. Your cabin air filter is located usually behind your dash on the passenger side of the car. Your air filter for your engine is located at the top of your engine in its own housing.
Why do air filters matter to you?
Air filters prevent debris from getting into your engine and damaging it. It also helps your car to run. Cars work on a combustion system. You need a spark and you need oxygen. Having clean filters also increases fuel economy. Cabin air filters protect the breathing air from pollen and dirt.
Signs something is wrong:
You’ve notice a drop-in fuel efficacy
Your car sounds funny
Your car has a check engine light
Reduction of horsepower
Your car is misfiring
Smell of gasoline
Black smoke and/or flames coming out of the exhaust
Below are examples of clean and dirty engine air filters