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Can You Drive Without A Catalytic Converter?

A car comprises numerous parts, but are they all necessary for it to run smoothly and efficiently?

The catalytic converter is one of those parts that is never really given much thought, as it just tends to run in the background.

Unless there’s a serious problem or it’s been stolen, there’s never any real reason to worry about it.

For this reason, it begs the question of whether a car can run without this particular part.

If you’re wondering, “can you drive without a catalytic converter?” the answer is yes, but only short distances are advised.

Read along as we break down whether this car part is needed or not.

How Does A Catalytic Converter Work?

Catalytic Converter

A catalytic converter, also known as the “cat,” can be found near the exhaust outlet on most modern cars.

The cat converts harmful emissions found in the vehicle’s exhaust gases into less harmful substances.

These harmful substances include hydrocarbons, nitric oxide, carbon monoxide, and nitrogen dioxide.

The catalytic converter changes them into slightly safer substances, such as water vapor and carbon dioxide, through chemical reactions.

The catalytic converter interior usually has a honeycomb structure with a coating that contains a catalyst.

A catalyst is responsible for changing the chemical structure of exhaust gases.

A catalyst is usually made from precious metals such as platinum, rhodium, and palladium, which makes them quite valuable.

This means that these parts are usually salvaged and recycled if the car is scrapped.

However, these valuable metals also mean that thieves tend to target catalytic converters.

Will My Car Run Without A Catalytic Converter?

Yes, generally speaking, a car will run without a catalytic converter as long as it’s been replaced with a suitable alternative, such as an exhaust pipe that’s a suitable size.

There may be a few reasons why driving without a catalytic converter might be necessary, such as if it’s been stolen or needs to be replaced.

Catalytic converters have been engineered to last the lifespan of the vehicle.

If you do have an issue with the fumes from the exhaust or your engine is running rich, the converter may get clogged or damaged, and a replacement will be needed.

What Happens When You Take Out The Catalytic Converter?

Although you can drive a car without the catalytic converter, it won’t run as well as it did before.

Below, we’ve outlined some things you can expect to happen if you remove the converter.

The engine error code and check engine light will be triggered

The catalytic converter is an important component of the vehicle’s exhaust system.

How effective it is, depends on the post-cat sensors that can be found on the exhaust.

If the exhaust fumes aren’t being filtered anymore, there will be increased levels of carbon monoxide and hydrocarbons.

This change will be picked up by the oxygen sensors, and they’ll send signals to the electronic control unit, or ECU, to change how the fuel is mixed.

Usually, this will cause the check engine light to come on and will trigger the engine trouble signal, which indicates an issue with the catalytic converter.

The exhaust will sound different

A catalytic converter works to mute the exhaust sound. Without one present, the sound from the exhaust will be a lot louder, and it’ll have a more gravelly tone.

If it’s replaced with a well-fitted exhaust pipe, the noise won’t be as loud, but it’ll still be noisier than if the converter was fitted.

The engine performance and fuel economy will be compromised

If the ECU recognizes a change in the exhaust fumes, it will try to improve it by decreasing or increasing how much fuel mix is in the cylinders.

When it comes to today’s cars, taking the catalytic converter out will increase the levels of carbon monoxide or hydrocarbons, and this can’t be fixed by changing the fuel mixture.

This usually forces the electronic control unit to change to an air-to-fuel mix because the signals that are being sent from the oxygen sensors are out of range.

Unfortunately, this will decrease the vehicle’s fuel-saving abilities.

If the check engine light comes on, it can hurt the engine performance too.

The ECU might also reduce how much power is available until this problem has been fixed.

Is It Illegal To Drive Without A Catalytic Converter?

This depends on which state you live in.

Some have laws on emissions testing that your car must pass. In this case, you could be fined for not having a converter.

But, in the states without these laws, it’s more common for vehicles to be driven without a catalytic converter.

However, except for specific scenarios, it is illegal to remove the catalytic converter.

To find out the laws where you live, take a look at your state’s website to find the guidelines.

There are also scenarios where a vehicle doesn’t need a catalytic converter.

For example, if the car is registered as an off-road-only vehicle, in some states, a converter is not needed.

Why Do Cars Still Work Without Catalytic Converters?

A catalytic converter doesn’t belong to the vehicle’s internal mechanical system that makes it work, and neither is it part of the driving or brake system.

Because of this, your vehicle will still start and run without the converter.

This is good news if you do need to use your vehicle without one, but there may be negative side effects if you do.


How long can you drive a car without replacing a catalytic converter?

Most of the time, you can drive for many miles with a partly blocked catalytic converter.

The initial sign of an issue is typically an error signal that’s triggered by the oxygen sensor.

When the engine is working properly, a catalytic converter will usually work the length of the car’s lifespan.

They typically only stop working if the exhaust gases are contaminated with coolant or engine oil.

Does removing the catalytic converter affect the engine?

No, removing a catalytic converter won’t cause damage to the engine.

However, you’ll probably experience reduced engine power and poor fuel economy.

What does a car sound like without a catalytic converter?

One word to describe the sound of a car without a catalytic converter is noisy!

The sound your car makes is the first sign that your converter is gone.

Your car will roar when you start it, and it will be much louder than it was before.

The volume of your vehicle will increase as you drive along – pressing the gas pedal will make the exhaust even louder.

The louder noise is caused by the exhaust system not working properly because of the missing converter.

How much are stolen catalytic converters worth?

Unfortunately, catalytic converter theft is on the rise because of the precious metals that are used in the converter interior.

Thieves can get between $100-$150 for each one; however, it can cost drivers up to $3,000 for a catalytic converter replacement.

Final Thoughts

Knowing that you can drive without a catalytic converter can offer reassurance if you do need to drive with that part missing.

But, although you can drive without one, there are side effects both legally and mechanically.

As we mentioned earlier, it’s illegal to remove catalytic converters unless under very strict guidelines.

If you discover you’re a victim of catalytic converter theft, report it straight away, so there are no legal consequences.

Either way, it’s good to know that you can get home without a catalytic converter if there’s an emergency!