Dirty Engine Air Filter? Here’s How to Tell & What to Do

November 4, 2021

Strange noises, smoke from the exhaust, poor acceleration ‐ these are just a few of the effects of a dirty air filter on engine performance. It's an essential component to keeping your engine healthy and one of the simplest car components to replace on your own. But what exactly does an engine air filter do and how do you know when to change it? Keep reading to learn how to tell if you have a dirty engine air filter, how to change your engine air filter, and more.

What Does an Engine Air Filter Do?

The engine air filter is just one of the different types of car filters that help your vehicle perform well. In order to create power, your engine needs to combine air and fuel for combustion. This requires a lot of air constantly flowing to the engine from the outside. The engine air filter's job is to help keep dirt, insects, and other road debris from getting sucked into the engine and causing damage. This is not the same as a cabin air filter, which helps clean the air as it enters a car's passenger area.

Over time, engine air filters can get clogged with debris and limit the amount of airflow that reaches the engine. It's important to clean or replace your engine air filter on a regular basis ‐ otherwise, your engine might suffer from a significant decline in power and performance.

Can a Dirty Air Filter Cause the Check Engine Light to Come On?

Yes, a dirty air filter is among the hundreds of potential causes for a check engine light. This is because a clogged air filter changes the ratio of air to fuel during combustion. With less engine airflow, fuel burns at an excessive rate and leaves behind a buildup of carbon deposits. Oxygen sensors in the exhaust system will detect increased emissions from the rich air-fuel mixture and trigger a check engine light.

When Should You Change Your Engine Air Filter?

Most engine air filters should be replaced every 15,000 to 30,000 miles, or approximately once per year. However, if you live in a particularly dusty area or regularly commute in stop-and-go traffic, your air filter will likely need to be replaced at a more frequent interval. You can check your owner's manual for a filter replacement interval specific to your vehicle model.

Signs You Have a Dirty Engine Air Filter

While a check engine light is commonly caused by dirty engine air filters, it's not the only sign your filter may need changing. Look out for these other symptoms of a bad engine air filter:

Signs You Have a Dirty Engine Air Filter

While a check engine light is commonly caused by dirty engine air filters, it's not the only sign your filter may need changing. Look out for these other symptoms of a bad engine air filter:

Reduced Fuel Economy & Horsepower

If you drive with a dirty engine air filter long enough, one of the first things you'll notice is a decline in your vehicle's fuel economy and overall power output. That's because the engine tries to compensate for the decreased airflow by burning more fuel to produce enough power. The good news is that only older, carbureted cars (pre-1980s) are likely to experience a sharp decrease in fuel efficiency from a clogged air filter. Most newer cars use an onboard computer to calculate and adjust fuel usage according to airflow.

Even if your fuel economy isn't impacted, you may notice that your car doesn't accelerate as quickly as you're used to. The limited airflow through a dirty engine air filter hurts the engine's ability to produce power, which may cause your car to feel jerky or sluggish when you press on the accelerator.

Reduced Fuel Economy & Horsepower

If you drive with a dirty engine air filter long enough, one of the first things you'll notice is a decline in your vehicle's fuel economy and overall power output. That's because the engine tries to compensate for the decreased airflow by burning more fuel to produce enough power. The good news is that only older, carbureted cars (pre-1980s) are likely to experience a sharp decrease in fuel efficiency from a clogged air filter. Most newer cars use an onboard computer to calculate and adjust fuel usage according to airflow.

Even if your fuel economy isn't impacted, you may notice that your car doesn't accelerate as quickly as you're used to. The limited airflow through a dirty engine air filter hurts the engine's ability to produce power, which may cause your car to feel jerky or sluggish when you press on the accelerator.

Engine Misfires

A misfire occurs when there is incomplete combustion inside your engine. When airflow is restricted through the air filter, the improper air-fuel ratio results in unburnt fuel moving through the engine as soot. This soot builds up on spark plugs and limits their ability to create a spark during the combustion process. As a result, you may experience engine misfires or even trouble starting your car.

Strange Sounds from the Engines

When your car is idling normally, you should be able to hear and feel the consistently smooth vibrations of the engine's rotations. If your engine air filter is clogged, however, your engine essentially cannot breathe. As a result, you may hear popping, coughing, or sputtering noises under the hood from fouled spark plugs and engine misfires.

Black Smoke From the Exhaust Pipe

Decreased airflow from a clogged filter often causes some fuel to go unburnt during the combustion process. Unburnt fuel typically leaves the exhaust pipe in the form of black smoke from leftover fuel ignited by the heat in the exhaust system. If you notice black smoke coming from your tailpipe, you should have your car inspected right away.

Gasoline Smell When Your Car Starts

When you start your car, the exhaust system is not yet hot enough to burn the excess fuel caused by a dirty engine air filter's poor air-fuel ratio. Instead of smoke from the tailpipe, you will likely smell gasoline.

The Filter Is Visibly Dirty

Of course, you can always visually inspect your engine air filter to see how dirty it is. Air filters are usually located inside a covered housing near the engine. Simply remove the cover and take out the filter to inspect it for dirt, bugs, leaves, and other debris. You can shake out the large pieces of debris, but if the filter itself is very dark from trapping thousands of miles worth of dirt and pollution, then it's time to replace it.

How to Change Your Engine Air Filter

New to DIY car maintenance? Don't worry! Replacing your engine air filter is one of the simplest at-home car repairs there is. Just follow these steps:

1. Locate the air filter housing under the hood. This is typically a plastic box near the engine.
2. Remove the air filter cover by loosening any clamps or removing the necessary screws.
3. Remove the filter by hand. Filters are typically rectangular and made from cotton, paper, or foam.
4. Clean the filter housing with an air hose or vacuum to remove any dust and debris left behind.
5. Insert the new, clean air filter into the housing, making sure the rubber rim faces up.
6. Replace the cover and re-secure it with its clamps or screws.

Nissan OEM engine air filters are durability-tested to last and custom-made to fit your Nissan engine. Order a new one online today!