Can a Car Run without a Catalytic Converter? Is it legal?

Catalytic converters are the filter of a car’s exhaust system. They clean your car’s emissions to reduce pollution.

It is standard equipment that is virtually present in every car. But there are often situations where Catalytic Converters get clogged and fail your engine. 

This article will explain if it’s possible to run a car without a catalytic converter and answer more questions in great detail. 

Can a Car Run without a Catalytic Converter? 

If your catalytic converter stops working, you can still drive your car after removing it. Catalytic converters are standard in all cars but are not mandatory for the proper functioning of a vehicle. Driving without one will not damage your engine or other components in any way. 

Even without the catalytic converter, your exhaust will have emissions. And for as long as your car can properly emit pollutants, it will work fine. It is just that the smoke will be darker and more poisonous.  

What is a Catalytic Converter for? What Happens When you Drive without it? 

A catalytic converter is an exhaust filter. It’s an emission control device that controls the level of pollutants coming out of your exhaust. Introduced in the ’70s, catalytic converters are standards in all vehicles. And the federal and state laws need you to have one installed on your car.   

A catalytic converter is an integral part of the exhaust system. If you have ever looked under your car, you would see a square or cylindrical bulge before the tip of the exhaust pipe. That’s your catalytic converter. 

These converters are made to last till the life of the car. And they have only one job, cleaning your exhaust emission as much as possible. To do so, a catalytic converter uses chemical reactions to convert harmful smoke into Co2 and water vapour. 

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Working of a Catalytic Converters

The insides of a Catalytic converter are made of a honeycomb structure. This structure is coated with a type of catalyst. The Catalyst works as an agent to initiate a type of chemical reaction. Platinum, Palladium, and Rhodium are three most common substances used as a catalyst. 

Once the burnt petrol gas from the engine gets to the catalytic converter. The catalyst initiates a reaction that converts gases like nitric oxide, carbon monoxide, nitrogen dioxide, and hydrocarbons into Carbon dioxide and water vapor. 

To do so, the converter operates at over 400 degrees, using the engine as the main source of its heat. The effectiveness of the Catalytic converter is decided by the number of precious metals (catalysts) used inside of it. The catalyst is precious metals that make converters an expensive piece of equipment. 

Types of Catalytic Converter

Catalytic converters are of multiple types as well. You have diesel cars with two-way catalytic converters. These converters are generally used for hydrocarbon and carbon monoxide emissions. 

While three-way converters are the most commonly used converters in gasoline cars, they are particularly used for converting nitrogen dioxide along with hydrocarbon and carbon monoxide. 

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Are there any Positives of Driving without a Catalytic Converter? 

While removing a catalytic converter might sound bad, there are some reasonable pros to it. 

Increase in Power

Cars without a catalytic converter have shown improved engine performance. You will often find modded cars with straight pipe exhaust because of the performance boost. This happens due to the lack of backpressure caused by the converter. 

When a converter is placed in the exhaust system, it gathers the emission, then the reaction happens, and exhaust gases come out. While this might happen in seconds, it slows the overall process of building a back pressure on the engine. 

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But when the converter is removed, it also removes the backpressure, which means the engine emission comes directly out at greater quantity. Allowing the engine to work at its best, hence improving the overall performance.   

Cooler Engine Operation

The Catalytic converter not only gathers the emissions. It also collects the heat to function properly. With the converter gone, the hot smoke comes out at a faster rate. This keeps the exhaust system relatively cooler, reducing the overall operating temperature.  

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Better Fuel Efficiency

Again with the converter gone, the overall load on the engine is also reduced. Allowing the engine to produce the same power but with less fuel burnt. With the emission leaving faster than before, the rate and efficiency of the combustion inside the engine are also increased, allowing the car to achieve better fuel efficiency. 

Variable Fuel Options

Catalytic converters are good for normal gasoline. But performance fuels have lead mixed in. While that is good for the engine to produce more power, it is bad for the converter as the catalyst inside might react the other way. Removing the Catalytic converter gives you the option to use high-performance fuel. 


Can you get a Ticket for Driving without a Catalytic Converter? 

Driving a car without a catalytic converter is illegal in most states. If your car is found without a catalytic converter, your car will not only fail the emission norms. But you would most likely pay a hefty fine of $250. 

You don’t have to pay the fine if your converter is stolen. But that is when you have reported the theft to the officials. Otherwise, you would be charged with “tampering of the emission control device. 

You must also remember that it is a violation of policy to both sell and install used Catalytic converters. 

Does a Car Sound Different Without a Catalytic Converter? 

A catalytic converter also works as a muffler, muffling the exhaust sound and making it a bit more pleasant to the ears. Removing it will make the exhaust extremely louder as there is nothing to insulate the loud combustion noises. A car with straight pipes uses the same method to create defining exhaust sounds with fire-spitting exhaust. 

However, if you have to remove your converter for some reason., using another kind of exhaust system can help you muffle the exhaust noise. But it will be louder than it was before.   

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How Much does it Cost to Install a New Catalytic Converter?

Installing a new catalytic converter is a costly job. Depending on your needs, a brand new catalytic converter can cost anywhere between $500 to $2500. Add another $50-$150 in labor cost.

The prices of a converter vary depending on the type of metal inside it and the materials used to construct it. The Catalytic converter you need is also affected by the type of exhaust you have and what number they are in. While most cars with dual exhaust use one catalytic converter. Some cars do have two catalytic converters in their exhaust system.    

There are also cheap catalytic converters available in the market for as low as $100. However, these converters are not at all durable and will start to fail after a few months.

The costliest catalytic converter last year was for a Ferrari F430 at $3,700. And it needed two of them. 

Note: One thing to remember before buying any catalytic converter, make sure that it has a federal warranty which is mandatory for all emission parts.

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Why are Catalytic Converters Often Stolen? 

Catalytic converters are stolen due to the precious metals available inside them. Metals like Platinum, Palladium, and Rhodium are rare and expensive. On average, a converter has about 3-7 grams of platinum but can vary depending on the manufacturer. 

With Platinum at $36 for 1 gm, 7 gm of it alone makes a lot of money, making them a favorable choice of theft. While car scrappers pay $50-$250 for a salvage converter, the precious metals inside are double the price. A stolen converter can sell for $300- $500 in the black market. 

Over the last two years, the US states of California, Texas, Minnesota, North Carolina, and Illinois have recorded the most thefts of the catalytic converter. And Toyota Prius is the most targeted car of all time. 

How to Prevent a Catalytic Converter from being Stolen? 

While there is not much you can do to prevent the theft, you can take some precautions. 

Identify the Target

First and foremost, identify what type of cars are often targeted. While Toyota Prius is one, trucks and SUVs are often hit. A quick call to your local car shop can give you a better idea. Don’t worry if you have an EV, though. Only gas cars that advertise their low emissions are one with higher chances of theft. 

Mark your Converter

Spray painting your converter with bright colors and marking your car serial number will make them more traceable. Colors like bright orange and red stand out from a far distance. 

Install Anti-Theft device

Anti-theft devices for Catalytic converters are available in the market. Depending on the type, they can range anywhere from $200-$800. There are cages made of steel that is fitted over the converter, making them hard to remove. A similar functioning steel shield is also widely available in the market. 

For a cheaper approach, you can get some steel wire welded to the catalytic converter and your car to keep it from being stolen.