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Dangers of a Car Air Filter Box That’s Not Sealed Properly

Car Air Filter Box Not Sealed

The air filter box under the hood of your car houses the air filter which is responsible for keeping dirt, leaves and debris from getting sucked into the combustion chamber of your engine.

An air filter box that isn’t properly sealed can throw P0420 and P0430 codes.

These are low-efficiency catalyst codes which suggest that the oxygen levels for the engine are below the ECU’s desired threshold.

If the air filter box has only been open for a short time, there’s not much risk of damage.

But if you operate your car for a long period of time without an air filter properly in place. Catastrophic damage to the engine is expected – even small quantities of dirt and debris can reduce the lifespan of your engine.

Let’s explore this component of an automobile’s air flow system to find out more about how it works; the importance of maintaining a good seal; and other symptoms you can expect from an air filter box that’s not sealed. We’ll also consider some recommendation to ensure a proper seal.

The Air Filter Box is a Part of the Air Intake System Which Works with the Engine

The air intake system is important for bringing in outside air into the engine’s combustion chamber – this is the area above the piston within a cylinder.

Every time a piston goes down air gets sucked into this combustion chamber through the intake valve.

This fresh oxygen then mixes with fuel which is sprayed into the combustion chamber via fuel injectors to cause a small explosion.

This explosion forces the piston back down which is what causes your car to move forward or backward.

The Air Filter Box Also Works with the ECU, MAF Sensor and O2 Sensor(s)

The Air Filter Box Also Works with the ECU, MAF Sensor and O2 Sensor(s)

As more air enters the engine through the intake system the air filter located in the air filter box filters out harmful contaminants from entering the combustion chamber.

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Put another way, an air filter box encloses the air filter to further help prevent dust and debris from getting sucked into the engine.

But an open-air filter box can lead to issues with the ECU, MAF sensor and O2 sensor. These components help measure things like air flow and pressure.

But when dust and debris rests on them it causes faulty readings that can throw P0420 and P0430 codes which can cause – among other problems – your car to run too fuel rich or lean.

Furthermore, without adequate air intake caused by a clogged air filter, the engine is starved of oxygen and fuel can’t burn properly leading to lower MPG (miles per gallon).

A Proper Air Filter Seal is Crucial for Filtering Out Contaminants to the Engine

To block contaminants and prevent air leaks, an air filter must fit snuggly within the air box.

But not all air filter seals are created equal.

Many vehicles use drop in air filters which don’t always have the best seal.

There’s a lot of heat under the hood of any vehicle with an internal combustion engine which can cause such air filters to become distorted. Even a slight distortion can compromise the amount of force required to seal the air box.

A car with an air filter box that’s not properly sealed can lead to air filter bypass.

Air Filter Bypass

What is air filter bypass?

This happens when fresh air coming from outside the engine is allowed to bypass the air filter – outside air is allowed to pass around the air filter instead of through it.

This unfiltered air then goes straight into the combustion chamber.

If you drive your car through areas with extreme conditions such as gravel, dirt, construction sites, road buildings and areas of farming activity. Your car is at risk of breathing in contaminated air.

Even minor air bypass can damage an oxygen sensor, catalytic converter and mass air flow sensor.

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Symptoms of a Broken Air Filter Box

The condition of the air filter box can make a huge difference on your car’s performance.

A properly sealed air filter enhances fuel economy, increases engine life, lowers emissions and boosts acceleration.

But a broken air filter box can lead to any of these five symptoms:

Decreased Performance

A dirty air filter prevents your engine from receiving clean oxygen resulting in sluggish throttle response.

Decreased Fuel Economy

If the engine can’t get enough fresh air because the air filter box isn’t maintaining a proper seal, then the engine compensates by using more fuel to deliver the same level of performance.

Fuel Smell

A likely symptom is the smell of more fuel than normal when you start your car or when it’s in operation due to the engine running fuel rich.

Engine Noises

You know what your car sounds like when it’s running optimally. Strange engine noises could be a telltale sign that the engine isn’t getting enough airflow.

Black Smoke

Insufficient air supply means your engine runs rich. This fuel-rich mixture doesn’t burn completely resulting in what looks like black smoke coming from the tail pipe.

Ensure the Air Filter Box is Properly Sealed

Below are some of the things I would do if I noticed any signs of an air filter box that’s not properly sealed:

Inspect the Air Filter Sealing Surfaces

What you’re looking for are dust trails that would indicate an improper seal. Things like missing housing latches also indicate an improper seal.

Check for Dusting

Dusting is when debris and dust have actually been pulled straight through the air filter. Remove the air filter and check for any debris that may have accumulated below it.

Examine the Ductwork

This is the tube connecting the air filter box to the air intake side of the engine. Examine for splits, cracks or tears. Anything that would allow air to bypass the air filter.

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Look for Damaged Filter Housing

The engine compartment is a hot place. Heat can distort the edges of the air filter preventing the air filter box from maintaining a perfect seal around the air filter.

Why You May Consider Performance Air Filters

Why You May Consider Performance Air Filters

Paradox: You want fresh air to come into your engine, but you don’t want it accompanied by dust and debris.

A thick air filter will do a good job of filtering out unwanted particles. But makes it hard for the engine to breathe.

This is why I like performance air filters.

They’re designed to let in more of the stuff you want into your engine while blocking out the stuff you don’t want.

Clamp Air Filter

Another alternative to the factory air filter box that can create a better seal so that dust and debris doesn’t get sucked into the engine is a clamp air filter with heat shield.

This system replaces the air filter box entirely with a cone air filter that clamps onto the air intake inlet right by the MAF sensor.

And in place of the air filter box goes a heat shield to keep the incoming fresh air colder than the rest of the engine.

Cold Air Intake System

This is my personal favorite air system modification. It’s relatively inexpensive and installation is pretty straightforward.

The larger diameter of the intake tube ensures more cold fresh air is fed into the engine.

The result is better performance.

And the cone filters that come with cold air intake systems are designed to filter out 98 to 99% of the dust and debris that threaten to wreak havoc on your engine.