How to Tell if Your Car Air Filter Needs Changing

Checking the air filter in a car engine

Knowing when your car air filter needs cleaning is important. Not only does a clean oil filter improve the overall performance of your vehicle, but it also improves gas mileage, acceleration, etc. In today’s world of high gas prices, increasing a vehicle's gas mileage is important to most of us. Did you know that having a clean air filter, depending on the make and model of your vehicle, can increase your gas mileage by as much as 14%? Also, your vehicle's acceleration can be improved by as much as 11%.

A car engine requires 10,000 gallons of clean air for each gallon of gasoline burned, so you can see the importance of maintaining a clean air filter. The following four steps will help you maintain your car's air filter at its optimum efficiency as well as to help you know when you should change the filter.

Step 1 - Take Notice of your Gas Mileage

gas gauge measured in dollar signs

Pay attention to the gas mileage your car is getting. A common symptom of a dirty air filter is a decrease in gas mileage. By maintaining a clean, efficient air filter, you can save on fuel costs. By checking your gas mileage at least monthly you will be able to notice any unusual decrease in gas mileage due to a dirty filter.

Step 2 - Note any Spark Plug Problems

A dirty air filter greatly impedes the amount of air flow to the engine, which in turn causes an overly rich air-fuel blend. Overly rich air-fuel can then pollute the spark plugs which will, in turn, cause your engine to miss. You will notice this when your car idles roughly and you have problems starting it.

Step 3 - Note the “Service Engine Soon” Light

A fuel mixture that is too rich will increase deposits on the engine which will most likely be the reason for the "Service Engine Soon" light to appear. If this light comes on, you should check your air filter to see if it is dirty and needs replacing.

Step 4 - Note the Appearance of the Air Filter

dirty air filter

If your air filter is brand new, it will look white or off-white. If you examine your air filter and note that it is full of debris or has darkened in color, this is an indication that it is time to replace the filter. When examining your air filter, you should do it in the light of day or with a flashlight. Because pollen and dust, which you cannot easily see, can also clog up your air filter, it is important that you replace the filter about every 12,000 to 15,000 miles. Follow the guidelines in your vehicle’s Owner’s Manual. If your vehicle is being driven on dirt roads or in city traffic with a lot of stops and starts, you will need to replace the air filter more often.

Step 5 - Take Notice of Your Vehicle’s Ability to Accelerate

If you car seems unable to accelerate as well as it usually does, it may be time to replace your filter.