Catalytic Converter: Everything You Need To Know

Cars, when running, release too many fumes and gases. Which are also referred to as emissions. Emissions cause air pollution. Nitrogen oxides, carbon monoxide, volatile organic compounds, and benzene are among the air pollutants released into the environment by motor vehicles.

Harmful fumes contribute to adverse effects on human health. Thus, the Clean Air Act, an air quality law was enacted in the United States in 1963 and amended many times since then. Under the CAA, is the National Emissions Standards for Hazardous Air Pollutants – standards set to reduce and control hazardous air pollutant emissions. 

In compliance with the air quality law, exhaust emission control devices are installed in vehicles. A catalytic converter is a type of exhaust emission control device; a very important part of a vehicle’s exhaust system.

What Is Catalytic Converter

The role of the catalytic converter is it converts toxic gases into less toxic end products like carbon dioxide and water vapor. The catalytic converter is unsurprisingly made of tough materials like platinum, rhodium, or palladium because it needs to endure high operating temperatures.

But despite the durability of the materials, the device can still break down due to issues with engine performance. When a vehicle has a bad catalytic converter, is it still possible to drive it? Can someone drive a vehicle without a catalytic converter?

Technically, the answer is yes. You can still run the vehicle even without the catalytic converter. Some people prefer driving vehicles not having a catalytic converter to save on fuel efficiency. However, vehicles made since 1975 have built-in catalytic converters.

Removing the device is not legal and getting caught driving without it will put you into a very serious problem and will be required to pay penalties. But if you’re driving a vehicle with a bad catalytic converter, you will not be fined for it. What are the symptoms of a bad catalytic converter?

Bad Catalytic Converter Symptoms

1. “Check Engine Lights” warning is On

This warning sign will be lit up on your dashboard. Though there may be other reasons why the “Check Engine Lights” warning appears, if you have a bad catalytic converter, then you will see that sign. 

Check engine control light on a vehicle dashboard.

2. Poor acceleration

Catalytic converters get clogged due to carbon buildup from excessive heat from unburned fuel. An engine needs a good exhaust system to allow it to run at peak power. But if the converter gets clogged up, a lack of power when accelerating will be encountered.

3. A foul smell (like rotten eggs) coming from the Exhaust

When the converter is in bad condition, it fails to change sulfide to sulfur dioxide – a colorless and odorless substance. When the transformation doesn’t occur, unburnt gasses with a foul smell from hydrogen sulfide exit the exhaust system.

4. Failed Emission Test

Emission testing is done by inserting a sensor inside the car muffler.

To ensure that the vehicle is correctly burning fuel and not emitting harmful gasses, it has to pass a smog test. A smog test is done every few years. If your car’s catalytic converter is in poor shape, then a failing smog test result is most likely.

5. Reduced Fuel Economy

A clogged converter will cause a low airflow. Due to low airflow, the car will burn more fuel than it necessarily needs. Because of improper exhaust flow, you need to hit the gas pedal more.   

6. Rattling Noise

You will hear a rattling noise coming from the broken parts of the honeycomb material located inside the catalytic converter. Breaking is due to the extreme heat coming from beneath the vehicle while driving. You will hear really loud rattling sounds when you start the vehicle.

If this occurs, the catalytic converter must be replaced immediately to prevent loose parts from getting into the exhaust system and then into the muffler. When the exhaust systems and muffler get blocked, you won’t have the chance to start your vehicle.

Some might ask if they decide to continue driving their car with a defective catalytic converter, then how long can it last? Well, the answer to that is – indefinitely.

A catalytic converter is being removed from a garage.

Though driving with a bad catalytic converter is not too critical, you can drive your car as usual, as long as some small parts of the catalytic converter are plugged. But when the catalytic converter is plugged in and a drop in engine performance is observed, you can no longer run your vehicle.  

Catalytic Converter Security

Due to the location of the exhaust system and the costly metals included in it, catalytic converters are prone to theft. Stolen exhaust systems are common in old model trucks since they can easily be dismantled from the vehicle due to high ground clearance. Catalytic converter theft can be prevented. Here are some steps to follow to help avoid theft:

  • If a secure garage is not accessible, make sure to park your vehicle close to building entrances and well-lit areas.
  • Ensure that the catalytic converter is welded to the vehicle’s frame. This will make it difficult to be dismantled.
  • Installing a cage-like metal material to serve as a cover for the exhaust system will help.
  • Consider installing a dash camera and/or a car alarm with a vibration alert sensor.
  • Mark or engrave the vehicle’s identification number to the converter to prevent the item from getting sold easily and for traceability.
A cage-like anti-theft cover for a catalytic converter.

Benefits Sans Catalytic Converter

Though it is highly recommended to use a catalytic converter, some are not convinced. Here are some beliefs on the benefits of not using a catalytic converter:

  • Converters reduce engine power; when removed, engines will have more horsepower. 
  • Without a converter, there’s a clearer and more identifiable exhaust tone.
  • The vehicle engine’s workload is minimized and the engine has a low running temperature.
  • The absence of a converter allows more fuel options.
  • Removing the converter will reduce pressure on the engine, allowing it to perform better.
Mechanic checking car engine temperature.


Having read the article, you already know the importance of using a catalytic converter. It was also explained that you can still use your vehicle as usual without it. To sum up, driving without a catalytic converter is possible but not legal.

A catalytic converter is an exhaust emission control that transforms pollutants and toxic gases into environment-friendly by-products. Thus, it is safer to drive a car that has a well-conditioned catalytic converter. If you need to use your vehicle without a catalytic converter due to malfunction or theft, drive with caution in nearby areas and have your catalytic converter replaced right away.

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About Brock Rangel

Hi, I am Brock, and I am the lead editor/photographer for TheCarColony. I have been a mechanic for over 14 years now, and I am here to spread my car knowledge across the web!

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