Car Air Filter Problems? 8 Most-Common Problems & Solutions

Your car’s air filter screens out contaminants like bugs and dirt before they can enter your engine. When it’s clean, your engine runs great. When it gets dirty, it will start to cause more problems than you expect.

There are 8 main symptoms indicating your engine air filter is dirty. We’ll cover each problem and how to fix it.

#1 – Your Car Engine Loses Power

Your air filter screens contaminants out, but it also allows air to pass through to enter the engine.

At idle, your engine doesn’t need a significant amount of air to run efficiently. At speed, the amount of air required goes up tremendously.

A clogged air filter will restrict the airflow and prevent the required amount of air from entering the engine. It will feel sluggish and won’t make the same power as it used to when the filter was new.

changing air filter / air cleaner

How to Fix It

To check the air filter, you’ll need to remove the cover from the air filter housing. The housing may be held together with screws or snapping clips, and it may require simple tools to remove the top of the housing.

Once you have the filter out, you can hold it up to the sun. If you can see sunlight through the filter element, it should be sufficiently clean to re-use. If the element is not translucent, it should be replaced.

There are aftermarket air filters that can be cleaned with a soapy water solution. Once it is dry from the cleaning, you can spray the filter element with an oil that will enable better filtering of contaminants.

These filters can last up to 1 million miles and may outlast the car itself.

#2 – You Have A Check Engine Light (CEL) Illuminated

Newer cars with onboard diagnostic systems use multiple sensors to verify how the engine is performing.

When it detects a problem, it will illuminate the Check Engine Light (CEL) in the gauge cluster. This notifies you that something is wrong, and a dirty air filter can trigger the light to appear.

How to Fix It

If your Check Engine Light is illuminated, you can use a hand-held scan tool to plug into the data connection under the dashboard.

The tool will communicate with your car’s computer and display what diagnostic trouble code has been logged in the system.

A clogged air filter can trigger a code indicating low airflow through the airflow sensor.

A clogged airflow is simple to replace. You may need simple tools to open the air filter housing, remove the dirty air filter, and replace with a new one.

Once the new filter is installed, your scanning tool should be able to delete the diagnostic trouble code stored in your computer and it will turn off the CEL light in your gauges.

#3 – Your Fuel Economy Starts To Decrease Rapidly

Your engine requires a specific ratio of air to fuel to burn efficiently. When the ratio of air to fuel is out-of-balance, your fuel economy will start to decline.

It will start slowly, but the more you drive with a dirty filter, you’ll get less and less miles per gallon in fuel economy.

Tank by tank of fuel, your odometer will show fewer miles every time you fill up.

How to Fix It

Most drivers will spend a few minutes after filling their fuel tank to calculate their latest fuel mileage.

Divide the number of miles driven on the recent tank of fuel by the number of gallons to refill the tank and you’ll know how many miles per gallon you drove on the last tank of fuel.

If you calculate a decline in your fuel economy, it’s easy to check the filter for cleanliness. If it is dirty, and you can’t see sunlight through the element, it’s time to replace it with a new one.

#4 – Your Engine Develops A Misfire Condition

Your engine should mix air and fuel at a specific ratio to run well.

When there is more air in the ratio than required it is considered “lean”. When the fuel is at a higher ratio, it is considered “rich”.

In either case, whether lean or rich, it can cause a misfire for your engine. Your engine may pop and sputter or completely stall rather than run smoothly.

How to Fix It

Your engine will run smoothly when the proper amount of air and fuel are mixed for combustion.

If you have a car newer than the mid-1980s, you probably have a computer in your car that determines how much air and fuel to allow into the engine.

When the air filter is dirty, the computer will try to compensate for the reduction in airflow by reducing the amount of fuel injected into the engine cylinders. The computer has a finite amount of adjustment, and the reduced airflow from a dirty filter will eventually cause the engine to run poorly.

If you have a misfire from a dirty air filter, the filter should be removed and replaced.

If the computer has logged a trouble code, it should be verified with a hand-held scanning tool and deleted once the filter has been replaced.

#5 – Your Car’s Engine Emits Black Smoke From The Exhaust Pipe

Black smoke is an indication that your air-fuel mixture is out of balance.

Black smoke is caused by too much fuel being in the combustion chamber while your engine is running.

A dirty air filter will reduce the amount of air entering the engine, and it will cause the ratio of the air-fuel mixture to be biased to the amount of fuel.

Black smoke is an indication your engine isn’t burning the air-fuel mixture efficiently.

Read here to find out the reason for white smoke coming out of your car exhaust.

How to Fix It

Your car’s engine computer will try to compensate for a reduction in airflow and reduce the amount of smoke produced. It can only compensate so much before it hinders the engine from running efficiently.

If you see black smoke coming out of the exhaust pipe, it’s an indication your engine isn’t running well.

It’s easy to remove the air filter and check if it is clogged with contamination. If it’s dirty enough to reduce airflow, replace it with a new one.

#6 – Your Car Exhaust Smells Like Fuel

You’ve probably driven behind or stood near a car that smelled terrible as it ran.

A dirty air filter will cause your car to run rich, meaning there’s too much fuel in the combustion chamber for the amount of air available.

How to Fix It

If your car exhaust smells like fuel, your engine isn’t running efficiently. There is residual fuel in the exhaust gas coming out of the engine, and it’s a direct indication there’s a problem.

Checking the condition of your air filter is something you can do in minutes, and it will give you a starting point to finding the problem.

Open your air filter housing and remove the filter. Check if you can see sunlight through the filter element.

If it’s too dirty, the sunlight won’t be very visible. When the filter is very dirty, it’s time to replace it with a new one.

#7 – You Find Contamination In The Filter Element

If you change your own oil, you have a routine for maintenance on your car or truck. If you pay to have the oil changed, your service provider also has a maintenance procedure for changing the oil.

Inclusive of either option should be removing the air filter from the housing and checking if it is dirty.

You should expect to find dirt and bugs stuck in the filter, but other contamination may be an indication of a larger problem.

How to Fix It

Checking your air filter every few thousand miles is a good practice and it will help you understand how well your car is running.

Including the air filter check with every oil change is an easy way to remember when to do it, and you should have basic tools available in the car already.

If the filter is in good shape, you can use it further. If it’s too dirty to reuse, you can replace it with a new one.

If you find major contamination such as oil in the filter element, it may be a sign you need to do more inspection of your engine and accessory systems. Something is leaking oil and it’s collecting in your air filter.

#8 – You Hear Strange Sounds Coming From Your Engine

The last thing you want to hear coming from your engine is a strange noise. Dirty air filters can reduce the amount of air in your combustion process, make your car run poorly, and start to affect other systems in the car.

If your engine starts sounding terrible, it could be a sign of a minor or major problem.

How to Fix It

If your car starts to run poorly, always start with simple checks to diagnose why your engine isn’t running well. The air filter can cause many systems to run poorly, so check it as one of your first steps in the diagnostic.

Replace the filter if it’s dirty or shows major contamination. You can verify if it is causing a problem by removing it from the housing and starting your car.

If it is causing a problem, your car should run better without the filter installed. Just don’t drive it without the filter for a long distance. You don’t want contaminants entering the airflow sensor and engine because of a missing air filter.

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