Quick Facts About Car Air Filters
- You don’t need to replace your car’s air filter every time you get an oil change.
- A disposable engine air filter is good for about 15,000 to 30,000 miles, depending on driving conditions.
- Changing your car air filter is one car maintenance job that is easy enough to do at home.
The engine air filter in your car keeps contaminants out while providing the air it needs to run. Keeping this filter clean gives you optimal engine health, performance, and efficiency. A filter clogged with excessive dirt and debris will sap acceleration and worsen fuel economy.
So, how often should you replace this vital car filter? We’ll provide details and more.
What Is a Car Air Filter?
A car air filter prevents dirt, debris, and other pollutants from entering the engine. As you drive in heavy traffic, over gravel, and other daily driving, all the air containing pollution and dirt is pulled into the vehicle. Luckily, the filter only allows clean air to make its way to the engine before combustion, improving fuel economy and performance.
Like most air filters, it traps all the particles mentioned above, which will cause the filter to turn from white to a much dirtier appearance over time.
Car Engine Air Filter vs. Cabin Air Filter: What’s the Difference
Because your car operates with two primary air filters, we’ll explain how your engine air filter differs from your cabin air filter.
Car engine air filter: This filter protects your engine from damaging material entering critical components and its efficiency, as explained above.
Cabin air filter: This filter you’ll replace more often (1 to 2 times per year), and it keeps the cabin air flowing clean and free of allergens, dust, mold, and other contaminants.
When Should You Replace Car Air Filter?
Different car manufacturers offer different recommendations on how often you should change your car’s air filter. Still, there’s a consensus that a disposable filter is good for 15,000 to 30,000 miles, depending on driving conditions.
If you drive in particularly harsh conditions (e.g., heavy traffic in hot weather, unpaved roads, or frequent off-roading), change your filter more often, or about 15,000 miles between replacements. Remember to keep track of all service records to help clarify when your air filter was last replaced.
Some shops might try to talk you into getting a new air filter with every oil change, but that’s far too often. It might not seem like a big deal since air filters are usually pretty cheap, and replacing them isn’t a big job, but a polite “no thanks” can help you avoid getting a new one when it’s unnecessary.
Can I Replace the Car Air Filter Myself?
Yes. This is one car maintenance job that is easy enough to do in your garage. Most engine air filters are straightforward to access under the hood or in the glove compartment inside the vehicle. If you’re unsure where it is, consult the owner’s manual to clarify where and how to replace it. If you’re having difficulty finding the information you need in the manual, check for it online. A quick search using your car’s year, make, and model should give you the answers you need. Reviewing the manual or consulting the web will also tell you the part number for the filter to use in your engine.
Start by opening the air box by removing a few screws with a screwdriver (or sometimes with no tools). When the airbox opens, you’ll see either a flat, rectangular filter or a round, cone-shaped filter. A flat filter can usually be removed by hand, and a cone-shaped filter will usually be secured with a hose clamp that can be loosened and tightened with a screwdriver. Simply take out the old one, put in the new one, close the airbox back up, and it will be good for the next 30,000 or so miles.
It doesn’t hurt to do a quick visual inspection of the air filter you’re currently using if you’re not sure how long it’s been since you’ve replaced it. You don’t have to be a mechanic to spot an air filter that needs replacing. If it looks filthy and worn out and you don’t know how many miles are on it, it’s better to be safe than sorry and replace it, especially since it’s a low-cost maintenance item, and replacing it early doesn’t hurt anything.
Signs of a Bad Car Air Filter
While it may be hard to tell when to replace your engine air filter since you don’t see it daily, there are a few warning signs that it may be time. While you can always take a look at it, most of the signs you’ll be able to notice just by paying attention to your vehicle.
- The engine air filter is visibly dirty
- Reduced gas mileage
- You haven’t replaced it in over a year
- Reduced acceleration
What About Reusable Car Air Filters?
Some high-performance aftermarket air filters from brands like K&N and Injen claim that they’re suitable for the life of your car but need to be cleaned every so often to remain effective. These filters use more durable materials than regular disposable air filters, proving that replacement isn’t necessary. They also claim that improving airflow improves engine performance without sacrificing proper air filtration.
If you use a reusable air filter, clean it as often as the filter manufacturer recommends. Some aftermarket brands even offer a cleaning kit specifically designed for their air filters. Keeping that kit in your garage is not a bad idea to ensure you use safe chemicals on your filter.
It’s safe for most drivers to go about 30,000 miles between air filter replacements. If you’re driving in harsh conditions that throw a lot of dirt and debris at your car, you’ll want to adjust that number to about 15,000 miles, particularly if you go off-roading. If you’re using a reusable aftermarket filter, follow the manufacturer’s instructions closely on how to keep it clean and effective.
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Editor’s Note: This article has been updated for accuracy since it was originally published.
Your engine relies upon its air filter to keep dust and debris out of the engine. By providing a clean stream of air to the engine, an air filter ensures the engine gets the right amount of air needed to operate at its peak level.
Worn or dirty air filters will cause your engine to perform poorly; among the things you'll notice is that you’ll have less power and weaker acceleration. Your throttle response will be diminished as well. But how do you know if it’s time to replace your air filter?
One rule of thumb is to keep track of how long your air filter has been in place. The average recommended length of service is about 10,000 to 15,000 miles, which for most people is every year or so. But keep in mind that, as with most things related to your car, this is just a recommendation and it doesn’t take into account your individual driving situation.
If you’re driving in heavy traffic on a regular basis, your air filter is not going to last as long. You’re going to have a lot of stop-and-start driving, which places more demands on your car and will also cause your air filter to get dirtier faster. Driving in dusty or rural locations can also make your air filter’s performance decline more quickly, so keep in mind that where you’re driving will affect how long it lasts.
Knowing some of the telltale signs of a dirty or clogged filter can keep you from waiting too long to replace it. Here are five things to look for that might indicate it’s time for a new air filter.
1) Your Air Filter Looks Dirty
If you know where your air filter is located (you can consult your owner’s manual to find out where to look), you can do a visual inspection. If your air filter is clean, it should be white or off-white. Over time, as dust and dirt accumulate on it, the air filter will get darker and the dirt will be noticeable. When it starts looking dark and grimy, you might be due for a replacement.
2) Your Car Seems to Have Less Power
A clean air filter will help your engine perform better; on newer cars, it can increase acceleration by as much as 11%, and on older cars it can improve mileage by as much as 14%. Other signs that your air filter is affecting your car’s performance is a jerking movement when you accelerate — or by not responding as well as it should.
3) Your Check Engine Light Comes On
There are many different reasons that your check engine light comes on; it can be as simple as a loose gas cap or it can signal a bigger problem. One of those reasons can be that the engine isn’t getting enough air, so carbon deposits form in the engine and that triggers the light on your dashboard. When you take your car in to your mechanic, they’ll be able to do a quick scan to see what’s causing the problem and can tell you if it’s an air filter issue.
4) Your Car Starts Making Strange Sounds
Without enough air, your car’s engine isn’t going to sound like it should. If it’s coughing and sputtering, or if it vibrates excessively when you turn over the engine, there’s a good chance it’s begging for a new air filter. If you notice strange sounds specifically when your car is idling, you may have what's known as "rough idle." Read our topic on this to learn what causes rough idle and possible fixes.
5) Smoke or Flames Shoot Out of Your Exhaust When You Start the Car
One good indication that the air filter needs replaced is the presence of black smoke coming from your exhaust pipe(s) when you fire up the engine. You also might hear a popping sound or see a flame at the end of the exhaust pipe. This can happen when there’s not an adequate supply of air in the engine. Not all of the fuel will burn properly in the combustion cycle and it will leave the car through the exhaust. The flame occurs when the heat of the exhaust ignites the fuel in the tailpipe. If you’re noticing this happening in your vehicle, you should take it to your mechanic immediately, as it can create an unsafe situation.
How Long Will It Take?
Getting your air filter replaced is usually a pretty simple and straightforward procedure and can be done in just a few minutes. That’s especially true in older vehicles. Some manufacturers of newer model cars have changed the design of the engine to make more efficient use of space, and sometimes that means putting air filters in places that are harder to reach—which can slow down the process.
However, your mechanic can usually tell you about how long it will take, and can check it during an oil change.
Getting your air filter replaced can be part of an overall tune-up service that will help you get better mileage and performance from your vehicle. It’s also a great way to catch any minor issues that can be resolved before they become bigger issues.