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Driving with a Bad Catalytic Converter (What to Expect + 5 FAQs)

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Experiencing a catalytic converter problem?
Want to know if driving with a bad catalytic converter is safe?

The short answer is NO. Driving a car with a faulty catalytic converter (CAT) is fairly unsafe.

But is it impossible? 
Also no. Let us elaborate. 

Driving with a bad catalytic converter has drawbacks, like lower fuel economy and frequent stalling. You could also receive a ticket or fine and fail an emissions test

Still confused? 
In this article, we’ll discuss what to expect when driving with a bad CAT and how long you can drive with a bad catalytic converter. We’ll also point out why you shouldn’t be driving with a bad catalytic converter

Additionally, we’ll inform you what to expect if caught driving with a bad catalytic converter and answer 5 FAQs related to catalytic converters

This Article Contains

Let’s break it down.

What to Expect When Driving With a Bad Catalytic Converter 

First, please understand we do not recommend driving with a bad catalytic converter. Although you may hear that driving with a faulty CAT isn’t too dangerous, let’s walk you through what could happen: 

A. When Your Catalytic Converter is Partly Clogged

A partly clogged catalytic converter won’t stop your car from running, it’ll only have a minimal impact on your vehicle’s performance. However, suppose you continue to drive with your partially clogged catalytic converter. In that case, you’ll experience engine misfire or loss of acceleration power. 

B. When the Catalytic Converter is Completely Clogged 

You shouldn’t drive your car if a catalytic converter is completely clogged. If you do, you can expect the restricted exhaust flow to hinder your engine performance, which leads to your engine idling for a few minutes and then dying. 

Worst case scenario, catalytic converter failure could affect your engine so badly that it won’t start.

Performance problems caused by your clogged converter can become especially dangerous in heavy highway traffic. On top of that, if smog checks are essential where you live, you’ll only be able to drive your car legally if you replace the broken catalytic converter. 

C. When the Catalytic Converter is Burnt

In some cases, your catalytic converter will eventually burn through completely. If this happens, you’ll have to replace it immediately. This problem usually happens if your engine burns too much oil, which means you have another problem to deal with. 

If you need more than the above section to deter you from driving with a broken catalytic converter, and you’re wondering how long you can keep going before your car ultimately gives in — let’s take a look.

How Long Can You Drive With a Bad Catalytic Converter?

You can drive your car indefinitely with a partially plugged converter. But we do not advise this as it’ll affect your car’s performance and possibly cause problems to build (on top of releasing unprocessed exhaust gas from your exhaust pipe.)     

Would you expect a professional football player with an injury to still take to the field? No, right? 

So you shouldn’t take the risk either. Better safe than sorry. 

In extreme cases, your car won’t even start because of a damaged catalytic converter. And over time, your catalytic converter could become completely fused — requiring immediate replacement.

Still not convinced that driving with a faulty catalytic converter isn’t a good idea?
Let’s explain why you shouldn’t consider driving with a damaged catalytic converter. 

Why You Shouldn’t Drive With a Bad Catalytic Converter

While driving, you are responsible for being careful on the roads and not causing harm to yourself, your passengers, and other motorists. Driving with a faulty CAT is not safe

Here are a few other reasons you shouldn’t be driving with a bad catalytic converter: 

1. Your Car Could Catch Fire

When traveling long distances, a failed catalytic converter can cause your engine to overheat faster than usual, possibly causing your car to catch fire.

If you suspect you’re experiencing a catalytic converter problem but cannot get it looked at immediately — avoid trouble by preparing to stop throughout your journey to let the car cool off.

2. It’s Illegal

The Environmental Protection Agency (EPA) maintains tight criteria for catalytic converters. 

Suppose you’re driving with a missing catalytic converter and get caught. In that case, you’ll be fined and unable to drive until you replace your catalytic converter. In most cases, replacing your catalytic converter is less expensive than being penalized.

3. It’s Bad for the Environment

Without a functioning CAT, you emit harmful pollution from the exhaust system into the environment every time you drive.   

You may be asking yourself why you should care. To paraphrase Starlord, you’re one of the people who live on Earth, so taking care of the environment is your responsibility. 

Additionally, if unprocessed exhaust gas gets into your car, the harmful carbon monoxide can make you ill. 

Let’s discuss what happens if you’re caught driving with a bad CAT.

What Happens When You Get Caught Driving With a Bad Catalytic Converter?

We’ve already established that driving with a bad CAT is illegal. 
So here’s what will happen if you get caught:

A. You May Fail an Emissions Test 

Vehicle owners must bring their vehicles for an emissions test at a specified date. A failed catalytic converter equals a failed Vehicle Emissions Inspection Test. 

If your emission levels are too high, you have 30 days to fix the catalytic converter. You can then resubmit your car for a free retest.

B. You Can’t Renew Vehicle Registration

Failing the emissions test will result in a denial of vehicle registration. And if you’re thinking you can skip the test, understand that avoiding the test has the same result. 

You’ll only be able to renew your registration once your exhaust fumes have suitable emission levels. So, putting off replacing your catalytic converter can lead to you not being able to drive your car on the road legally. 

C. You’ll Get a Fine

You can expect a $20 late fee for missing your appointed date for the emissions test by more than 30 days. Additionally, you’ll get a fine each time your vehicle is stopped and found non-compliant.

Every time you drive your car without passing the emissions test and get pulled over is a separate violation. Remember that each fine will be higher than the previous one — making it possible to get multiple infraction citations before your registration is denied. 

Multiple citations can ultimately become more expensive than simply replacing your catalytic converter.

Still have some queries about the converter? 
Let’s go through some frequently asked questions. 

5 FAQs Related to Catalytic Converters

Here are the answers to some burning questions related to your converter and catalytic converter repair:

1. What are Bad Catalytic Converter Symptoms?

If you have a failing catalytic converter, it won’t take long to know what a bad catalytic converter symptom looks like.

When experiencing catalytic converter failure, you’ll start to notice things like:

2. Can a Bad Catalytic Converter Ruin My Car’s Engine?

The short answer is yes.
A clogged catalytic converter can cause your vehicle to lose power, causing frequent and harder steps on your gas pedal. 

A clogged converter combined with spark plug misfires can lead to the overheating of your engine. It’ll soon give out if you ignore your check engine light and endure a sluggish engine. 

In fact, CAT converter issues don’t only lead to poor engine performance and toxic exhaust gasses, but also complete engine failure. Engine failure is much worse than any horrible smells or sounds associated with a bad catalytic converter symptom. 

3. Why is My Catalytic Converter Important? 

A catalytic convertor works to reduce harmful emission in your exhaust by neutralizing the toxic gas containing hydrocarbons, carbon monoxide, hydrogen sulfide, and nitrogen oxide. It transforms the toxic gas into less harmful exhaust gasses like carbon dioxide and water vapor. 

However, CATs are more than just emission control devices. 

Your converter works with other vital car parts, not just your exhaust — like the O2 sensors and ECU. This assists in maintaining the proper air to fuel ratio in your combustion chamber, which comes into contact with the spark plug and ignites. 

A correct fuel and air mixture in the combustion chamber helps ensure complete combustion, preventing issues like engine knocking or backfiring that are related to abnormal combustion.

4. Why is My Catalytic Converter at Risk of Getting Stolen? 

Your catalytic convertor contains precious metals like platinum, palladium, and rhodium that help reduce the harmful emission levels of your exhaust systemAs such, you need to protect your vehicle from catalytic converter theft. A stolen catalytic converter can be sold at a high price since it contains valuable metals. 

Platinum costs up to $1,000 per ounce, and palladium can easily cost about $2,000 per ounce. Reports from the NICB (National Insurance Crime Bureau) state that in 2019 there were 3,389 stolen catalytic converter cases reported. In 2020, catalytic converter theft victims reported 14,433 cases of a missing catalytic converter.

5. How Much Will it Cost to Replace A Catalytic Converter? 

You should expect to pay between $500 and $2,200 to replace a failing catalytic converter in newer cars (newer cars have a more complicated CAT and are more expensive to replace). A catalytic converter replacement in older cars will cost about $175 to $750.

The expensive metals used to make your CAT is part of what drives the high catalytic converter replacement cost. 

However, don’t let the high cost of catalytic converter repair deter you from fixing a damaged converter. Avoid opting for cheap repair alternatives like catalytic converter cleaner, as it might only offer a temporary fix. 

Closing Thoughts

Driving with a bad catalytic converter is technically possible, but it’s not advised. We’ve covered various reasons why you should not be driving with a bad catalytic converter, and we hope you’ll heed them. 

If you suspect your catalytic converter is faulty, call RepairSmith
Our expert mobile mechanics will come to you to diagnose and sort out the issue. 

At RepairSmith our mobile car repair and maintenance services are available seven days a week. We offer upfront pricing, a 12-month | 12 000-mile warranty on all repairs and convenient online booking.