The value and utility of an air filter’s role in your car’s engine is often overlooked. Your car engine runs on a mixture of air and gasoline. The air that mixes with the gasoline flows through the air filter. The quality and volume of the air coming through the filter can cause issues with the running and performance of your engine. Here are some signs that your air filter is dirty and may require changing.

1. It looks dirty: The most obvious sign that a vehicle’s air filter needs to be changed is that it looks dirty. If your air filter is difficult to locate for purchase or is expensive, you can clean it.

To clean a dirty air filter from your car, first open the hood and remove it. Vacuum the air filter to get the loose debris and finer dust off. After vacuuming the air filter, if you want to also wash it, fill a bucket with water and soap. A dish liquid soap or car wash soap diluted into a bucket of water should suffice. Place the air filter in the bucket with the soap and water, swish and swirl the filter around in the bucket and leave it to soak for a few minutes. Then take the dirty filter out of the water and shake off the excess water. Run the dirty air filter from your car under running water until the dirt, along with the soap solution, runs off and the water runs clear. Do not under any circumstances put the air filter back into the vehicle while the air filter is wet. Leave the air filter to dry. It should dry in approximately 15 minutes. Once the filter is completely dry, place it back into its compartment in the engine compartment.

If the air filter in your vehicle is an oiled air filter, there is a special cleaning solution required in order to clean it. So, the only value in cleaning it yourself is if you cannot find a replacement air filter for your vehicle or it is expensive. Remove the dirty oiled air filter from its compartment in your car. Shake off all dirt and debris. Apply the special cleaning solution liberally. Leave the solution on for 10 minutes to penetrate the air filter. Do not let the solution dry on the air filter. After 10 minutes, rinse the cleaning solution off the air filter under running water. The air filter should dry in approximately 15 minutes. You can speed up this process by using a hairdryer. Do not reinsert the air filter until it is completely dry.

Air filters should be cleaned or changed every 10,000 – 15,000 miles, or a minimum of once a year. Highway and city driving may require more frequent changing or cleaning.

2. Fuel economy has worsened: If you notice that your car is getting less mileage, this could mean that your air filter is dirty and needs to be replaced or cleaned.

3. Engine misfiring: Reduced air intake through a dirty air filter leads to unburned fuel, which creates a soot that collects on and around the spark plug that reduces its capabilities. The result is misfiring or jerking.

4. Weird noises from under the hood: A clogged air filter or resulting dirty spark plug can cause the engine to vibrate or to make coughing or popping noises.

5. Inefficient spark plugs: Spark plugs ignite the fuel and air mixture, the air that comes through the air filter. A dirty air filter creates build-up on the spark plugs which impedes their ignition ability.

6. Check engine light: A misfiring of the engine can cause the check engine light to come on. Depending on the year of your car and its systems, there are a variety of other air filter related issues that can trigger the check engine light to come on. Whether it is for the air filter, or other, when the check engine light comes on it is time to take the car in to be seen by a licensed professional. The check engine light is not something to be ignored or put on hold until later. Some automotive places will run the diagnostics scanner for free. This would at least help you determine the cause of the problem to see if it is an issue that can wait for a short period of time if you cannot immediately afford to fix the problem.

7. Reduced acceleration: A dirty air filter can lead to less responsiveness when you accelerate.  A clean air filter can improve acceleration or horsepower by approximately 11%.

8. Black smoke or flames emitting from exhaust: Less air intake through a dirty air filter means that there is leftover fuel not being burned during combustion. This leftover fuel now exits the car through the exhaust causing black smoke or flames.

9. Gasoline smell: If gasoline is being emitted from the vehicle due to a dirty air filter in your car, this gasoline will ultimately exit through the exhaust pipe, causing a strong smell of gasoline. A strong smell of gasoline should be immediately checked out by an automotive professional.

10. Rough idle: The average car should idle between 900-1,000 RPMs, revolutions per minute.  A dirty air filter will cause a change in the idle of the engine. If you notice a change in the RPMs or smoothness of the idle, a change or cleaning of the air filter is likely required.