6 Symptoms of a Dirty Air Filter (& Replacement Cost)

Symptoms of a Dirty Air Filter

Of the many car maintenance tasks you must stay on top of, changing the engine air filter is a top priority. A dirty air filter can lead to numerous problems and make your everyday drive less enjoyable. It can also lead to paying more for the vehicle’s fuel because of excess consumption.

Thankfully, it’s not difficult or expensive to change the air filter in most cars. We review the top symptoms of a dirty air filter and look at how much you can expect to pay for a replacement. 

Dirty Engine Air Filter Symptoms

1. Power Loss

slow car acceleration

When the filter becomes dirty, it no longer allows enough air to reach the engine. Without the proper balance of air flowing through, the engine can’t run as it is intended. What you are left with is a reduction of power and acceleration.

You might notice this more frequently when you demand more of your vehicle, such as during towing or driving up steep inclines. However, any time that the vehicle feels sluggish, it’s wise to visually inspect the air filter. 

2. Strange Engine Sounds

check noise under hood e1609791600132

When the engine is running as it should, you should hear a familiar hum coming from the motor. However, when the filter becomes clogged, a lack of airflow can cause some strange sounds.

In some cases, you might hear a sputtering noise or a popping sound. It’s also possible to hear a whistling noise due to the obstructed airflow. The more buildup that is on the filter, the louder the noises can become. 

3. Check Engine Light

check engine light

When the filter becomes clogged, the flow of air into the engine is restricted. This inadequate supply means too much fuel is being mixed in. 

With more fuel being burned, the carbon deposits start to build up, causing the Check Engine Light to come on. When these warning lights illuminate, you can use a code scanner to hunt down the root of the issue. 

RELATED: Check Engine Light On – Meaning, Causes & How to Fix It

4. Reduced Fuel Economy

bad fuel consumption

To produce power and momentum, the car engine mixes air with gasoline. However, when the airflow is restricted, too much fuel gets pumped into the engine. When the motor runs rich, you find yourself using more fuel.

Any time that the car is using more fuel, it’s a sign that there’s an imbalance with the engine. Pay attention to how often you are filling up, so you can correct issues before they become major. 

5. Engine Misfiring

car misfires

Without the right amount of air entering the combustion chamber, the motor creates more unburned fuel. This extra soot builds up on the tips of the spark plugs.

When the plugs can no longer provide the right level of spark for ignition, the car will misfire and run poorly. You might also notice a rough idle or stalling as a result. 

6. Black Exhaust Smoke

black smoke from exhaust

In extreme cases, you are going to see a change in the exhaust smoke leaving the tailpipes. With an incomplete burn of the fuel in the combustion chamber, you will notice black or dark gray smoke coming from the rear of the vehicle.

The color is due to the unburned fuel mixing with the hot exhaust. However, it is also a symptom of a malfunctioning fuel injection system or a bad O2 Sensor.

Air Filter Location

Modern vehicles contain an engine air filter underneath the hood. You can find it in a rectangular-shaped cold air box, often in the front of the engine compartment, where it is easy to access.

If you have an older vehicle with a carburetor, the air filter location might be different. These cars use large round metal air cleaners that are nearly impossible to overlook.

The engine air filter should never be confused with the cabin air filter. The cabin filter keeps the interior air clean and free of contaminants. It is usually found in the glove box or behind the dashboard. 

RELATED: 10 Best Engine Air Filters for Cars

The Function of an Engine Air Filter

new engine air filter

The engine air filter is responsible for keeping contaminants, debris and dirt from getting into the engine through the air. It must remain free of clogs to ensure that the motor gets the right level of air for combustion.

The air filter replacement is part of regular car maintenance because it can become clogged over time. When it gets clogged, the air-fuel ratio in the combustion chamber becomes imbalanced, leading to numerous performance issues. 

Air Filter Replacement Cost

The average air filter replacement cost is only $10 to $30 for one made with paper material. In most cars, changing the air filter is a simple process that doesn’t involve any special skills or tools.

If you prefer to install a reusable air filter, you can expect to pay between $30 and $100, depending on your vehicle. These reusable filters can be cleaned out for longer use. 

The engine air filter should often be replaced every 12,000 miles or 12 months, whichever comes first. You can find the recommended replacement schedule in your car owner’s manual. However, if you notice any of the above symptoms, you will want to replace the filter sooner. Considering the low cost, it’s one of the first places to start with any engine performance issues.

Written by:

Magnus is the owner and main author of MechanicBase. He has been working as a mechanic for over 10 years, and the majority of them specialized in advanced diagnostics and troubleshooting. He has also been a motorsport (drifting) driver for over 5 years.