How to Tell if Your Engine's Air Filter Is Dirty

Mia Bevacqua
December 21, 2018

Your car’s air filter prevents dirt and debris from entering the engine while still allowing airflow. 

clogged air filterImage courtesy of Ryan Gsell/Flickr

When the engine is running, the filter creates a vacuum. As a result, air gets pulled through the filter, through the air intake, toward the engine. This air mixes with fuel and is then ignited inside the combustion chamber. 

In the past, when engines had carburetors, air filters played a greater role in vehicle performance than they do today. Modern vehicles have electronics and computers that can compensate for a dirty filter — at least, up to a point. But even today’s cars can struggle with an old, dirty filter.


Signs of a dirty air filter

In most cases, you won’t know the air filter is dirty unless it’s removed and inspected. But there are extreme instances when the fibers can get clogged enough to create noticeable symptoms, such as the following:

  • Reduced fuel economy: A restricted air filter may starve the engine of air, forcing it to work harder and use more fuel.
  • Poor performance: An engine needs the right amount of both air and fuel to perform well. A clogged filter can reduce airflow, causing a lack of power. Turbocharged engines are particularly susceptible, as they require significant flow to build boost pressure.
  • Illuminated check engine light: In rare instances, a restricted air filter can cause the engine to run rich (too much fuel, not enough air) enough to turn on the check engine light. Also, if the engine is turbocharged, lack of boost pressure from a clogged filter can trigger the warning.
  • Failed emissions test: If the car runs rich, it can fail an emissions test. But this scenario is uncommon with modern computer-controlled engines.

» LEARN MORE: Get an estimate for an air filter replacement

How to fix the problem

The fix for a dirty air filter is straightforward: replace it. Cleaning the air filter is not recommended, so don’t try blowing it out or shaking it free of debris. The only exception to this applies to some replacement filters, such as K&N, that come with a cleaning kit and instructions. 

To avoid problems, replace the air filter in accordance with the manufacturer’s maintenance schedule. You can find this schedule in your owner’s manual.

On most vehicles, air filter replacement is a simple task. The job can often be completed with simple hand tools, such as a screwdriver, or even without any tools at all. Of course, on some cars, the air filter is buried away deep inside the engine, making it difficult to access. Also, keep in mind that engines with twin-turbos have two air filters.

Take a look at your air filter; if the replacement appears doable, go for it. Otherwise, have it taken care of by a professional.


Mia Bevacqua

About the Author

Mia Bevacqua is an automotive expert with ASE Master, L1, L2 and L3 Advanced Level Specialist certification. With 13-plus years of experience in the field, she applies her skills toward writing, consulting and automotive software engineering.

1 User Comment

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By , May 27, 2018
Thank you for your Air Filter Repairing tips. I have 6 months old a California air compressor from It is generally silent and only produces 60 dB of sound. This compressor generates 130 psi max of pressure. I need to clean the air filter and repair some other parts. This high demand and contextual article helped me to how to clean my compressors air filter very easy. Happy to face this Guide. Thank you for your latest Guide

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