Yes, you could temporarily drive without a catalytic converter, and it won’t damage a modern car or engine.
But in the long run, it’ll emit harmful gas, sacrifice your car’s engine performance and fuel economy, and possibly get you in trouble with the law. This applies even if your catalytic converter has been stolen.
In this article, we’ll explain what catalytic converters do and why it’s illegal to drive without one. We’ll also cover what happens if you drive without a catalytic converter, how safe it is, and some helpful FAQs.
Let’s get started.
What Do Catalytic Converters Do?
A catalytic converter is part of a vehicle’s exhaust system designed to reduce harmful emissions.
Its primary function is to convert toxic pollutants produced from the combustion process and expelled in the exhaust gases into less harmful substances before they are released into the atmosphere.
The catalytic converter contains a honeycomb-like structure coated with precious metals such as platinum, palladium, and rhodium.
As the exhaust gases pass through it, the metals act as catalysts, promoting chemical reactions that superheat and break down harmful pollutants.
There are two main types of catalytic converters:
- Two-way catalytic converters primarily convert carbon monoxide (CO) into carbon dioxide (CO2) and oxidize unburnt hydrocarbons (HC) into water (H2O) and CO2. Two-way converters are generally found in older vehicles, many of which are still on the road today.
- Three-way catalytic converters are more advanced and can also reduce nitrogen oxide (NOx) emissions, converting them into nitrogen gas (N2) and oxygen (O2). Three-way converters are used in most modern vehicles and are more effective at reducing overall emissions.
By significantly reducing harmful emissions, catalytic converters improve air quality and protect the environment.
So what would happen if you suddenly had to go without it? Let’s find out.
Can You Drive Without a Catalytic Converter?
The short answer is yes.
Temporarily driving without a catalytic converter won’t damage your car’s engine in any way. However, it may cause some performance issues.
The real question is: Why would you want to drive without one? Driving without a catalytic converter will emit harmful exhaust gas into the atmosphere.
Plus, laws around catalytic converters and emission tests are very strict (for a good reason).
Unfortunately, these laws around the emissions test still apply even if your catalytic converter has been stolen.
Let’s take a closer look at the legal angle.
Is it Illegal to Drive Without a Catalytic Converter?
Yes, it’s illegal to drive without a catalytic converter in most states of the US. However, some exceptions made by the Environmental Protection Agency (EPA) make driving without a CAT legal.
While the law differs from state to state, it’s best to play it safe and ensure your vehicle always has a functioning catalytic converter fitted. The Clean Air Act of 1970 mandates that all vehicles must be fitted with carb-compliant catalytic converters from the factory.
What if your vehicle didn’t come with a catalytic converter?
We’re glad you asked.
Most cars manufactured before 1970 (when the Clean Air Act was instated) didn’t come with factory-fitted catalytic converters. For this reason, some states (like Georgia) will allow you to pass respective emission checks if your vehicle is older than 25 years.
We’ve established that it’s generally illegal to drive without a CAT.
Now, let’s explore the safety aspect.
How Long Can You Drive Without a Catalytic Converter?
Vehicles can be driven without a catalytic converter. There are vehicles in non-emission testing areas that have had their catalytic converters removed, but removing a cat-con is against the law in every state, even those that don’t enforce emissions standards.
If you remove the converter yourself (a reputable shop won’t usually do this for you), just know that intentionally disabling the emission system on a vehicle is considered a serious offense. And the government can legally fine you many thousands of dollars for doing so.
In the event your catalytic converter has been stolen, you’ll know as soon as you start your vehicle. The loud, booming idle is a giveaway that your catalytic converter has been sawed off.
You may be able to file an insurance claim to have the exhaust system repaired, although we recommend installing a catalytic converter protection shield preventatively.
Protecting your vehicle with an easy-to-install shield, such as one from Cat Security, can help you avoid theft altogether and save you thousands.
Is it Safe to Drive Without a Catalytic Converter?
Yes, you may be physically safe driving without a catalytic converter, but you won’t be legally safe (as mentioned above).
As a critical component of your car’s exhaust system, the catalytic converter reduces air pollution. So, driving with a broken catalytic converter (or no catalytic converter at all) won’t cause a crash.
Still, you’ll want to replace it as soon as you notice you have a stolen or failing catalytic converter!
Here’s why:
Driving without your car’s catalytic converter means you’ll expel very high concentrations of carbon monoxide — an extremely harmful emission. Most deaths caused by carbon monoxide poisoning occur while operating a vehicle inside enclosed spaces.
Plus, if you have a bad catalytic converter (clogged, broken, or faulty catalytic converter), it’ll severely hinder your car’s engine performance.
Let’s look at how driving without a cat converter affects your vehicle.
What Happens if You Drive Without a Catalytic Converter?
There are a few tell-tale signs if you have a bad catalytic converter — or if it’s just not there anymore!
Here’s what you’ll likely notice:
- Loud exhaust pipe sound: If you find your catalytic converter stolen, the first thing you’ll notice is a louder exhaust pipe noise. You’ll also notice an increase in your car’s exhaust system volume when revving the engine — which is very difficult to ignore.
- Poor performance: Without a complete exhaust system, you’ll notice a significant decrease in engine power. Weak acceleration, stalling, and lack of power on inclines are dead giveaways that you may have issues with your car’s catalytic converter. You may also notice an illuminated Check Engine Light, which happens when your car’s ECU no longer picks up oxygen sensor readings from the exhaust.
- Strong exhaust smells: Without a catalytic converter, your vehicle may emit potent smells (as well as deadly carbon monoxide gas, which has no smell at all). If ignored, these exhaust fumes could seep into the cabin, potentially causing a deadly mistake.
- Reduced fuel economy: When your car’s ECU notices a change in the concentration of exhaust fumes from the oxygen sensor, it’ll try to mend the imbalance by altering fuel levels and exhaust flow from the cars engine cylinders. This will likely cause your fuel consumption to increase significantly. Additionally, if the Check Engine Light is illuminated, the ECU might restrict engine power until the error has been resolved.
- Emissions failure: Vehicles must have carb-compliant catalytic converters fitted in every state. If you go for a yearly inspection without one, you’ll fail the emission test.
Still, have a few doubts?
Other FAQs About Catalytic Converters
Here are answers to questions you may have about catalytic converters:
1. Why Do Catalytic Converters Get Stolen, and How Do I Prevent It?
Catalytic converters contain many precious metal components, like palladium, rhodium, and platinum. These valuable metals react with nitrogen oxide to filter out any harmful gas. They also have high resale value for a catalytic converter thief.
To make matters worse, catalytic converters have very few identifying markers except a serial number. Once it’s off your vehicle, you probably won’t see it again.
Unfortunately, if you’re the owner of a low-emissions vehicle, you’re more likely to have your catalytic converter stolen, because the CATs on these models tend to have higher concentrations of valuable metals.
While it’s illegal to pay for scrap metals with cash, some merchants unfortunately still allow their purchases.
If you’d like to prevent catalytic converter theft, there are a few ways to do it:
- Install an anti-theft device on your catalytic converter: This will trigger an alarm when the device detects any tampering with the cat converter and works similarly to a vehicle alarm system. Anti-theft alarms are the best way to prevent catalytic converter theft.
- Paint your catalytic converter: Although it’s not the most effective way to prevent catalytic converter theft, painting your CAT will add an identifying marker — and, hopefully, make it easier to track down a stolen catalytic converter.
Tip: It’s best always to have car insurance for possibilities like catalytic converter theft. While having car insurance won’t save a stolen catalytic converter, it’ll take some weight off having to replace it.
2. How Much Does it Cost to Replace a Catalytic Converter?
Due to the precious metal components inside, a catalytic converter replacement isn’t cheap. A new catalytic converter can set you back between $400-$3000 — and that’s just for the part.
Considering labor, you could end up paying at least $1000 to replace your vehicle’s stolen or faulty catalytic converter.
Final Thoughts
Driving without a catalytic converter (or with a broken catalytic converter) can cause some serious air pollution and harm to your health. As a car owner, it’s your responsibility to get your vehicle’s catalytic converter repaired or replaced, even if it’s stolen.
While a catalytic converter replacement or repair can be pricy, it’s better to get them done as soon as possible — or risk facing unpleasantries with the law and Environmental Protection Agency during your next emissions test!