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Can You Drive a Car with a Bad Catalytic Converter?


A catalytic converter is a crucial part of your vehicle’s machinery. Its function is to convert harmful emissions into less harmful gases. But, can you drive a car with a bad catalytic converter? Here’s the answer:

Although you can drive a car with a bad catalytic converter, it’s not safe. See, on a running engine, the cylinder temperature shoots up to 2500 degrees. The exhaust gases are meant to move into the catalytic converter, but they stay inside the engine when the catalytic converter gets blocked, causing the engine to overheat.

You might want to learn more about the function of the catalytic converter and why it’s essential that you have a properly working catalytic converter in your car.

Let’s dive in.

What’s the Function of a Catalytic Converter?

Catalytic converters are placed in the exhaust system of a vehicle and work by using a catalyst to convert pollutants into less harmful gases before they are released into the atmosphere. The catalyst used in a catalytic converter is usually made of platinum or palladium.

Therefore, a working catalytic converter is essential for reducing emissions and protecting the environment. Not only that, but an effectively working catalytic converter improves your vehicle’s efficiency and in turn, its overall performance.

Symptoms of a Bad Catalytic Converter

Generally, a catalytic converter doesn’t go bad that easily, unless another part in your vehicle’s machinery malfunctions and gets ignored over time. But, catalytic converters can also wear out with time.

Let’s talk about the red flags that could be an indication that your catalytic converter needs to be replaced.

old catalytic converter on hand

Performance Issues

This is the most prominent red flat for a bad catalytic converter, and can include:

  • Lack of power
  • Sluggish performance
  • Black smoke from the exhaust
  • Slow speed
  • Stalling

If you encounter all of these issues, it’s probably because of a blockage in your car’s exhaust. Also, if your engine is misfiring, it could quickly destroy the catalytic converter.


Another symptom of a bad catalytic converter is overheating of the engine. A clogged catalytic converter traps the gases inside the engine, which heats it pretty quickly.

But, what should you do to check its temperature? Use an infrared temperature gauge to check the temperature of the front and back of the catalytic converter. Its front side should be at a lower temperature than its backside. If the backside is cooler, the catalytic converter is probably clogged. Don’t forget to turn the engine on before doing that.

Do a Visual Inspection

One of the first things you want to do is visually inspect your catalytic converter for cracks. Then, tap on the catalytic converter using a rubber mallet. Make sure the engine is off and cooled down before doing that.

If the catalytic converter emanates an unusual sound, like particles bouncing around, it’s most likely gone bad.

Lower Mileage

Another symptom of a bad catalytic converter is lower miles per gallon. If you feel your car isn’t giving the fuel average it normally gives, there’s a possible issue with your catalytic converter.

How to Clean a Catalytic Converter

Now, the good thing is that you don’t have to remove the catalytic converter. A replacement can cost you up to $2000, and you want to avoid that expense as much as possible. So, before you replace it, try cleaning the catalytic converter and making it work.

Run Diagnostic Check

If you’re not sure about whether your catalytic converter has really gone bad or not, what you can do is run a diagnostic test with a tool. Here is a great option.

After running the test, if you get error codes P0420 to P0439 or oxygen sensor codes, the catalytic converter is blocked.

Keep the Fuel Tank Half-Full

While cleaning your catalytic converter, you’d need to run your engine for about 30 minutes, which means there needs to be enough fuel in the tank.

Add the Cleaner

Next, add a catalytic cleaner solution to the converter. You can use any exhaust system cleaner, but here is a good option on Amazon.

Run Your Engine for 30 Minutes

Once you add the cleaner solution to the fuel tank, run your engine for about 30 minutes at 2500 RPMs. This is to make sure that the cleaner solution effectively reaches the problem areas and cleans the catalytic converter.

Run Diagnosis Again

Next, run the diagnostic test again to see if the problem persists. If it does, it’s most likely because the catalytic converter is broken or cracked. If you no longer receive any error codes and the engine light is turned off, it means your catalytic converter wasn’t broken and was just clogged.

Otherwise, you’d need to replace your catalytic converter, which isn’t going to be cheap. You can expect to pay as much as $2000 for a catalytic converter replacement. The final cost might vary depending on the rarity of your car and labor costs.

Replacing a catalytic converter takes about an hour. Old catalytic converters tend to be simpler to replace than the modern, more advanced ones.

Final Thoughts

So, can you drive a car with a bad catalytic converter? Technically, yes, you can drive your car without a catalytic converter. But, is it safe? No.

See, a bad catalytic converter means less fuel average, poor performance, and potential internal damage. So, why take the risk? The good thing is that you don’t have to replace your catalytic converter unless, of course, it’s broken or cracked.

You can just get a cleaner, add it to the fuel tank, run your car, and let the engine do the rest of the work. That’s way better than replacing a catalytic converter, which can cost up to $2000.

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