Can You Drive with a Bad Catalytic Converter?

By Tom Newman

It’s something that many vehicle owners ponder: can you drive with a bad catalytic converter?

This small but critical component helps mitigate the risk of your car polluting the environment, and you could have a more serious issue on your hands.

So, what does it mean for your vehicle? Is it safe to drive it? Let’s delve into driving with a bad catalytic converter and what you should do if you suspect yours is failing.

What is a Catalytic Converter?

A catalytic converter is part of your car’s exhaust system’s design to break down harmful pollutants such as carbon monoxide, hydrocarbons, and nitrogen oxides so that they can be exhaled through the tailpipe in less harmful forms.

It is necessary to put a stop to air pollution and keep your car within environmental laws. On average, a catalytic converter usually lasts around ten years or even longer, but various problems with engine operation can primarily result in it failing earlier.

What Are the Signs of a Bad Catalytic Converter?

Knowing whether or not you can drive with a bad catalytic converter requires you to know the signs of failure that can prompt its demise.

If you’re wondering what those red flags might look like, here are the most common:

Reduced Engine Performance

A bad catalytic converter will have a serious impact on your engine performance, making it difficult to accelerate or maintain higher rates of speed.

Check Engine Light

If your vehicle’s check engine light is on, it could be due to a failing catalytic converter. A diagnostic check can confirm this.

What Are the Signs of a Bad Catalytic Converter?

Strange Sounds

A rattling noise under your vehicle could suggest that the inside parts of your catalytic converter have collapsed.

Excessive Heat

A bad cat can overheat your vehicle. Translation: you could end up with a fried engine.

Can You Drive with a Bad Catalytic Converter?

The short answer is yes but with some major caveats. Here’s what you need to know.

1. Short Term Driving

Yes, you might drive a bit if your catalytic converter has only failed. It isn’t completely clogged but the engine will misfire, and you will be emitting more pollutants than usual. It’s not a good idea. It is just a short term solution. 

2. Long Term Consequences

But drive too long with a bad converter, and the reverse can happen.

The catalytic converter that’s clogged, or worse still, totally failed, can end up damaging your engine, so it runs poorly or not at all. Or it might even compromise the entire exhaust system. Again, this is not what any of us want.

3. Legal and Environmental Concerns

Some places even make it a crime to drive with a bad one. When a catalytic converter is bad, your car is spewing much more carbon and other additives than even a used running car is allowed to emit

It will not pass an emissions test. It could get you into legal trouble if you even tried to drive it.

What Should You Do If You Suspect a Bad Catalytic Converter?

If you suspect that your catalytic converter is failing, you must act quickly. Here’s what you can do:

Have a Diagnostic Test: Go to a mechanic and have the mechanic confirm whether the catalytic converter is really the issue and how badly damaged it is.

What Should You Do If You Suspect a Bad Catalytic Converter?

Replacement: Replacing the catalytic converter could be necessary, depending on the severity of the issue. This can be a costly solution, but the vehicle must be operational, legal, and environmentally right.

Avoid Long Trips: If you have to drive with a bad catalytic converter, try to keep your trips short to slow damage to the car. 

How To Fix a Bad Catalytic Converter?

If your vehicle is missing power and not meeting emission standards, you likely need to repair a faulty catalytic converter. Here’s how you do it.

1. Diagnose the Problem

  • Check For Symptoms: Check whether the catalytic converter is actually the problem: a check engine light, sluggish response from the engine, rattling noises, or excessive exhaust heat could be filled signs. 
  • Use an OBD-II Scanner: If you’ve got the check engine light on, grab an OBD-II scanner. Plug the scanner into the computer in your dash, and it will retrieve the diagnostic trouble codes (DTCs). You need to dig through the scanner’s library to narrow down the possible causes in your particular case. Codes P0420 and P0430 are usually a catalytic converter issue.

2. Inspect the Catalytic Converter

  • Visual Inspection: Jack up the vehicle and use jack stands to support it while you inspect the catalytic converter for visible damage. Look for dents, rust, or cracking.
  • Check For Clogs: If you suspect a clog, knock on the catalytic converter with a rubber mallet. If it rattles, the pieces inside are probably breaking apart, and your converter will likely need to be replaced. 

3. Consider Temporary Solutions

  • Fuel Additives: Some fuel additives claim to ‘clean’ the catalytic converter – invariably, they have a temporary effect but won’t tap deeply enough to clear really bad problems. Use them as a stop gap measure while you plan something more permanent.
  • Cleaning the Converter: At times, a catalytic converter cleaner can be used to clean the catalytic converter. Pour the catalytic converter cleaner into the fuel tank by adhering to the catalytic converter cleaner instructions and by running the engine to determine if performance is restored.

4. Replace the Catalytic Converter

  • Purchase a New Catalytic Converter: As long as the diagnostic tests indicate a bad catalytic converter, the next step is to replace it: Buy a new converter (make sure to buy a direct fit for your vehicle’s make and model) and fix it.
  • Removal of the Old Converter: Just jack up your vehicle and look around in the exhaust system of your car to find your catalytic converter. Then, unbolt it from the exhaust manifold and the exhaust pipe using a wrench. Be aware that the bolts can be rusted or seized.
How To Fix a Bad Catalytic Converter
  • Install the New Converter: Put the new converter in place and tighten it with the bolts, making sure neither the clamp nor the pipe are leaking.

5. Test the Repair

  • Start the Engine: Once installation is complete, start your car to check that the new catalytic converter is working properly. The check engine light should turn off if the fault has been corrected.
  • Emission Test: You can book an emissions test to ensure your car meets environmental standards. 

6. Regular Maintenance

  • Prevent Future Issues: Keep your car clean and well maintained to prevent issues with your catalytic converter in the future: replace the oil on time, use only high quality fuel, and keep the engine running smoothly to prevent premature failure.

FAQs on Can You Drive with a Bad Catalytic Converter

What Happens If I Drive with a Bad Catalytic Converter?

It can cause a loss of performance due to incomplete fuel combustion, higher emissions output, and sometimes damage to other parts of the exhaust system. It also means your car will not pass an emissions test.

How Do I Know If My Catalytic Converter is Failing?

Reduced engine power, a check engine light, noisy rattling noises, and an excessive amount of heat coming from under your vehicle are all indications that your catalytic converter is malfunctioning.

Is It Legal To Drive with a Bad Catalytic Converter?

In some areas of the U.S., driving with a faulty catalytic converter is actually against the law. This would increase your emissions and likely make it impossible for you to pass an emissions test, which would be required for you to drive your car legally.

Can a Bad Catalytic Converter Damage My Engine?

Yeah, because you’ll have a rough running engine, which may damage the engine at the same time. Get it fixed.

How Much Does It Cost To Replace a Catalytic Converter?

You could replace your catalytic converter for as little as $900 or as much as $2,500, depending on what you drive.

Conclusion

Technically, you could keep driving with a broken or inefficient catalytic converter, but it’s not wise to push it for too long.

The risks to your car, the environment, and your wallet make having your car repaired as quickly as possible the best option.

If you suspect you have a damaged catalytic converter, bring your car to your trusted mechanic for diagnosis and repair.

Keeping your car’s catalytic converter has long term benefits. Not only does it keep your car happy, but it keeps the air around you a bit cleaner, too.

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