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

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

Your vehicle’s air filter does a great job for your engine, protecting it from particles of dirt and debris that can enter the combustion chamber with air. At the same time it doesn’t restrict airflow, allowing the engine to breath and suck air that goes through the filter and air intake to the motor. This cleaned air is mixed with fuel and then ignited inside cylinders. 

Many decades ago, when most vehicles used a carburetor to prepare an air/fuel mixture, a bad air filter could significantly decrease performance. Thanks to electronic and computer systems in modern vehicles the performance of today’s cars and trucks is less affected by a dirty air filter, however, it can also be the case.

Is my filter bad?

As a rule, you will never know how dirty your filter is unless you take it off and inspect. However, a lot of dirt can make the filter fibers clogged enough to restrict airflow resulting in the following noticeable symptoms:

  • Increased fuel consumption. A dirty air filter can reduce airflow, so the engine will have to work harder and therefore use more fuel.
  • Bad performance. To run at its peak efficiency your engine needs the right amount of fuel and air to be mixed. A clogged filter restricts airflow and significantly reduces performance especially if you drive a turbocharged vehicle that requires a lot of air to maintain the proper boost pressure. 
  • Check engine light comes on. Sometimes a poor air filter can make the engine run too rich, which may cause the light to illuminate. If it’s turbocharged, the lack of boost pressure will also make the check engine light come on. 
  • Cannot pass the emission test. A too rich air/fuel mixture may not allow you to pass the emission test. Fortunately, it is not common for modern fuel-injected vehicles.