Car Air Filter: How to Check & Replace It

The modern combustion engine is a fantastic piece of machinery. As we all know, a car engine has many moving parts that work together at the same time to generate outputs like power and torque. It’s important to understand that an engine is only as good as what's put into it. 

Sadly, most people only realise this in terms of the fuel and oils that they use. Most people tend to overlook the other crucial part of the equation: the supply of good, clean air into the engine's chambers, allowing for combustion to take place.

Why Clean Air Is Vital for Combustion 

The supply of clean air is critical for an engine. If the engine sucked in air contaminated with dust or dirt, for instance, the combustion process would be a lot less efficient. Overall, the car wouldn't perform as best as it should.

Thankfully, modern cars are equipped with several filters. Some filter out the fuel that travels through the fuel line into the engine. Additionally, some filters ensure that only clean air makes it into the engine.

Let's be clear from the start: this article is talking about the engine's air filter, not the cabin or air-conditioning system's air filter.

Cabin Air Filter vs Engine Air Filter

Your car has two air filters which basically perform the same thing. The big difference here is that one filter is located inside your vehicle's cabin while the other one is under the hood for the engine.

Cabin Air Filter

The air filter inside the cabin is sometimes referred to as the air-conditioning air filter, which purifies the air that circulates inside the cabin. It removes dust, dirt, and sometimes even odours from the air. If this filter is in good shape, you and your passengers will be able to breathe easy on your trips.

Engine Air Filter

The filter under the hood does the same thing. It ensures that only clean, purified air enters the engine where it's mixed with fuel and then burned. A dirty cabin air filter can cause some discomfort to passengers, but a clogged engine air filter can do a lot worse. It will cause your vehicle to suffer from a decline in performance.

Signs Your Engine Air Filter Needs to Be Changed

Thankfully, there's a long list of signs that you can look out for to know when to change your engine's air filter.

Dirty Appearance

The first and most direct way of examining your engine's air filter is to pop the hood and look at it with your own eyes. A new and clean air filter will look white or off-white, while a dirty one will be dark and dusty.

Decrease Fuel Efficiency

Aside from that, the most common sign of a bad air filter will be a change in the car's performance. If you pay attention to the kilometres returned per litre of gas consumed, you'll notice a decrease in fuel efficiency. When your engine doesn't have enough oxygen coming in due to a dirty air filter, it'll end up guzzling more fuel than it should.

Engine Issues – Coughing, Misfiring, Rough Idling, Others

With a lack of proper air supply also comes problems like engine misfiring, rough idling, or even issues in getting the engine started in the first place. This may also cause the engine to make strange sounds like coughing and slipping instead of a natural, smooth humming sound.

Other Symptoms - Gasoline Smell, Black Exhaust Smoke

Since a bad air filter causes your engine to function incorrectly, it'll also affect what comes out of the engine itself. You may notice the smell of gasoline while driving, or black smoke and even flames coming out of your exhaust pipes. These are all late signs that your air filter needs to be changed because if these signs are present, that means your filter is dangerously dirty.

Remember: a combustion engine can only perform to its optimum if it has a supply of both clean fuel and clean air at the same time.

How to Replace Your Engine Air Filter

Replacing an engine air filter is one of the most straightforward car maintenance tasks to perform. Air filters are cheap, and you can get a mechanic to do it during your next oil change, or you could change it yourself.

Don't be afraid to watch a few YouTube videos to help you visualise the steps listed below. After all, you only need to learn how to do it once. When you get the hang of it, you'll be changing air filters like an expert the next time around!

Step by Step: How to Change Engine Air Filter  

Here are the necessary steps to changing the engine air filter:

1. Open your hood and find where the air filter box or housing is located. Usually, it looks like a black box and is held shut by clips on its side. These clips make it very easy for you to open and close the housing when necessary. Sometimes it's located on top of your engine, but in some cars, it might be on the engine's side instead.

2. Open the air filter housing and remove the old filter. Take a close look at the filter to see how dirty it is.

3. Put in the air filter and make sure that it fits correctly. If you're unsure, check your car owner's manual or any instructions that might be printed on the filter's box.

4. Close the air filter housing and lock it in place with the clips.

Benefits of Changing Engine Air Filters Regularly

As with the other filters in your car, it's a good idea to change your engine air filter regularly and before it gets filthy. By doing that, you'll keep your engine's fuel efficiency high and prolong the life of your engine. After all, an air filter is very cheap; certainly cheaper than the loss in fuel efficiency and engine damage from running with a dirty filter.

How Often to Change Air Filter

Depending on the driving conditions you experience, it's good to change the air filter around every 20,000 kilometres or at least once a year.

Or, to keep things simple, you can have your engine air filter changed whenever you bring the car in for its regular maintenance or oil change.

Hopefully, the dirty air filter you’ve replaced has not yet caused any wear or damage to engine parts. If it has, have your car seen by a mechanic or an engine specialist. 

(Blog from

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