8 telltale signs that you need to replace your air filter

Updated Feb 23, 2021

Check out 8 signs that it’s time to replace that air filter right now!

Air filter is one of the most common car parts that you will hear during your car’s regular preventive maintenance check-up. Though the name sounds simple, and functions in simple ways, air filter is also one of the most important parts of the car as it helps to ensure that our vehicle runs smoothly.

Just a short refresher – air filter is a material composed of fibrous material that collects unwanted particles in the vehicle. These unwanted particles inclde dust, dirt, pollen, mold, debris and other unnecessary materials. Air filter prevents them from entering a car’s engine, radiator and other parts where air and fluid circulates.

How engine air filter works

Air filters, just like any other things, wear out as time goes by and if the car owner didn’t take care of it properly. With its work of maintaining the cleanliness and functionality of all other car parts that are exposed to air, it would have an adverse effect if not taken care of properly.

If our car’s air filter is not functioning properly, the debris will not be filtered as necessary and just like a human being’s lungs, the engine will have difficulty breathing. It then needs to work harder for the car to run smoothly. The effect will then be on the fuel efficiency of your car, as the engine needs more fuel to sustain running. More fuel, more money you’d spend to fill up your gas tank.

With these in mind, it is very important for us to know just when the air filter needs cleaning or replacing. If you don’t know the signs of a screaming-for-help air filter, Philkotse.com can help you out.

1. Decrease in Gas Mileage

Used to have an unbelievable fuel efficiency? Like you put Php 500 of fuel and it lasts you for a week of to and from the office? Then slowly you noticed that you need to fuel up twice a week and it doesn’t even last you till the weekend.

It could be a sign of a dirty, damaged or an air filter that already needs to be changed. When you notice a significant decrease in gas mileage, don’t ignore it – take your car into an auto shop for a quick check.

low fuel economy

A decrease in gas mileage is a direct result of a clogged or dirty air filter

2. Your car is having difficulty starting up

You are so at ease that even if you board your car at 7am, you’d be able to get to work on time. One day, 7am, just like any other day, you board your car and started up the engine – poof! Not starting. You just keep on turning those keys and trying to rev to warm up the engine, but the engine seems to be having a hard time starting up. Consequently, you were late for work, for the first time ever since you had that car.

starting up a car

If you're having a car start up problem, you could blame a dirty air filter because not enough air goes through the engine

This kind of problem could be a result of a dirty and neglected air filter. When your car’s air filter is dirty, the amount of air going to the engine to help it start up smoothly is limited – that’s why you’re having start up issues. Check your manual on how to remove your air filter and follow our instructions on how to clean your air filter properly.

If you’re uncomfortable doing it yourself, just take your car to a professional so they can check and attend it for you.

3. Rough Idling

Okay, so you start up your car and you usually let it idle for a few minutes to warm your engine up. If you experience your car vibrating, or producing unwanted, unusual sound coming from the hood like a coughing or sipping sound then you are possibly having damaged spark plugs – an aftermath of a dysfunctional air filter.

To ensure smooth idling, without vibrations or weird and alarming sounds coming from the hood, always be mindful of your air filter.

4. The dreaded “Service Engine” light comes up

Uh-oh – seeing the “service engine” light can cause us quite a panic. First thing we’ll worry about is the cost of having the engine repaired, or worst, replaced. We can be quite advanced thinkers especially when money is involved – but don’t fret too much. This service engine light might have lit up because of a dirty air filter. Why? Because with a clogged air filter, the engine receives insufficient air that it needs, therefore resulting to deposits inside the engine.

So next time you see this light, don’t press your panic button on just yet – check your air filter first if its dirty and if it is, clean it or have it cleaned by a professional.

service engine light

Dirty air filter doesn't allow the engine to get the necessary air it needs, hence the service engine light comes up

>>> Related: Cabin vs Engine air filter: What are their functions and differences?

5. Your air filter is just simply, dirty

If you’re a car enthusiast, then most probably you’re the type who checks everything in your car if not every day, at least once or twice a week. By doing this, you’d know if your air filter is already dirty or not and if it is, you should have the initiative to clean or replace it if necessary.

A clean air filter would look white or off white, so it’s pretty easy to know if it’s already dirty or not. By being aware of the condition of your air filter, you are avoiding future engine problems.

clean and dirty air filter

Sometimes we don't need to be complicated - simply, your air filter is dirty and neglected

6. Difficulty accelerating

If you notice your car having a hard time speeding up no matter how much you stepped on the gas, it could be an effect of a clogged air filter – because, again, the engine doesn’t get the right amount of air it needs to keep up with the speed you want. When this happens, take time to check your air filter.

7. Smoke coming from the exhaust

If you see smoke coming from the exhaust it could possibly mean that the engine doesn’t get the right amount of air it needs, resulting to fuel not burning properly and going out through the exhaust pipe. If you see a black smoke coming from your car, have your car checked by a mechanic.

exhaust pipe smoke

Another sign of dirty air filter is smoke coming out of the exhaust pipe

8. Gasoline smell

Another thing that can freak you out. Personally, I like the smell of gasoline whenever we’re in a gas station, but it could also make me feel nervous thinking that the car might just burn or explode anytime.

This gasoline smell goes along with the black smoke coming from the exhaust pipe because of the unburnt fuel. This is a sure sign that the air filter already needs to be replaced.

>>> Click here to get more helpful tips and advice for your car maintenance

Ivy Kristia Padura

Ivy Kristia Padura


Ivy is one of the first Philkotse's content writers. She finds joy in sharing her driving tips, particular for dealing with heavy traffic in Metro Manila, with other fellow drivers.

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