Symptoms of a Dirty Air Filter: How to Clean and When to Replace

Apart from fuel, oxygen is necessary for internal combustion engines to operate. They have air intake systems for the air to flow into the combustion chambers, mix with fuel, and support combustion. However, the air must be clean and free from debris—that’s where air filters come in.

An air filter is a device that is used to trap impurities such as dust, pollen, and debris from getting into the combustion chambers. Over time, it will get clogged and can no longer do its job well. Replacing or cleaning a dirty air filter regularly will help to ensure that the engine gets the clean air it needs.

Symptoms of a Dirty Air Filter

The best way to know if the air filter is dirty is to remove and inspect it. If it is dirty, you will see some dirt and dust on it. But without even inspecting it, you can still tell when the air filter is dirty if your car exhibits the following symptoms:

• Poor Fuel Economy

A dirty air filter will restrict air flow into the combustion chamber. This will cause the engine to run rich (too much fuel and too little air). An engine running rich will cause the fuel not to burn completely, hence poor fuel economy.

• Strange Noises from the Engine

When the air filter is dirty and the engine running rich, it can make the spark plugs to become fouled. This means that deposits will cover the spark plugs, causing the engine to produce strange noises.

If you inspect it and find it dirty, it is also good to check and replace the spark plugs in case they have been affected.

• Smell of Unburnt Fuel

Since the engine will not be burning fuel effectively, unburnt or partially-burnt fuel will escape through the exhaust pipe. This is where the smell of unburnt fuel comes from.

• Loss of Power

A dirty air filter can cause loss of power by restricting the amount of air that can flow into the engine. This causes the engine to run rich, which can lead to fouled spark plugs and loss of power. 

Cleaning and Replacement

You should check your car’s air filter as frequently as possible, more so if you drive on dusty roads—don’t wait for the symptoms. A good time to check and clean or replace it is during the engine oil change. If it looks worn out, the best thing to do is replace it with a new one. But if it only has a little dirt on it, you can clean it using compressed air or a vacuum cleaner.