Replacing an air filter is typically one of the easiest car care tasks. Usually, all you need to do is remove the airbox lid by releasing a few clips or undoing a few screws, and the air filter can be popped right out—it’s that easy.
Since most air filters are also relatively inexpensive, it’s a good idea to change your car’s filter regularly. When left unchecked, a dirty air filter can lead to various problems that make your vehicle less efficient and less enjoyable to drive.
What Does an Engine Air Filter Do?
Your car’s air filter traps contaminants within its fibers to prevent dirt and debris from entering the engine. The air filter also promotes clean airflow into the air intake system.
The air filter is located downstream from the engine, inside a housing that’s attached to the air intake tube. When the engine is running, the pistons move downward in the cylinders, creating a vacuum that pulls air through the air filter and into the engine. That air mixes with fuel and is then ignited, creating the energy to propel your car.
What Can Happen When Your Engine Air Filter Is Dirty?
Today’s computer-controlled vehicles use sensors to measure the amount of air entering the engine. Because of this, a dirty air filter has less of an effect on engine performance than it did in the past.
The computer can compensate for a dirty air filter—but only up to a point. When the filter becomes completely clogged (or close to it), there simply isn’t enough airflow to keep the engine running properly.
An air filter that’s seriously neglected can result in several problems, including:
Poor Engine Performance
A severely restricted air filter can starve your engine of air, causing performance problems, such as poor acceleration and rough running.
Turbocharged engines, which require an unobstructed air intake to build proper boost pressure, often suffer the most from a clogged air filter. Vintage vehicles with a carburetor are also prone to performance problems caused by a restricted air filter.
Increased Fuel Consumption
The engine has to work harder than normal to pull air in through a dirty air filter. That rise in energy expenditure often leads to an increase in fuel consumption.
Increased Tailpipe Emissions
In extreme cases, a dirty air filter can reduce engine airflow enough to create a rich running condition (too much fuel; not enough air). As a result, the engine will produce a greater amount of tailpipe emissions.
Illuminated Dashboard Warnings
Some late-model vehicles are equipped with an air filter life monitor that uses various sensors to detect a dirty air filter. A computer (often referred to as the powertrain control module), receives data from those sensors.
When the module determines the air filter requires replacement, it turns on a warning light on the dashboard, reminding the driver to replace the air filter. In some extreme cases, a dirty air filter (and the resulting engine performance problems) may also cause the module to turn on the check engine light.
How Often Should You Change Your Car’s Air Filter?
You can approximate how often your car’s air filter should be changed by consulting the vehicle manufacturer’s service schedule. The information can be found in your owner’s manual or supplemental service booklet.
But if you regularly drive through a dirty or dusty environment (e.g., dirt roads), you may need to change the filter more frequently than the vehicle manufacturer recommends. If your filter sees severe use, check it every 6 months/6,000 miles and replace it if it looks dirty. You’ll know it’s time for replacement when the filter element is dark and allows very little light to pass through.
How much does it cost to have the engine air filter replaced?
If you choose to have a professional replace your engine’s air filter, expect to pay (on average) $50 to $100 to get the job done. You can save money by replacing the filter yourself. Most OEM-style replacement filters cost less than $25. Of course, the exact price of the filter will depend on a variety of factors, such as the year, make, and model of your vehicle.
If you wish to replace your engine air filter yourself, you may refer to our DIY guide on how to change an engine air filter.