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Cracked Catalytic Converter : Symptoms, Causes & Solution [ 2022 Updated ]

Cracked Catalytic Converter : Symptoms, Causes & Solution [ 2022 Updated ]

The catalytic converter happens to be an expensive car component to replace. Thankfully, this component is very sturdy and resistant to corrosion.

Your car may not even require a cat converter replacement throughout its lifetime, especially if you take good care of it. However, at times, the component might get faulty.

If you end up with a cracked catalytic converter, you’ll have to replace it. A faulty cat converter can potentially cause your vehicle to fail emission tests, depending on the extent of the damage.

What Are the Symptoms of a Bad Catalytic Converter?

As the catalytic converter is a part of the exhaust system and lies under the car, you likely won’t notice any signs of damage unless you check it yourself. Check out these signs that point to a bad catalytic converter.

1. Unusual fuel consumption

A bad catalytic converter usually increases the vehicle’s fuel consumption. Especially when the exhaust system is in a clogged state, fuel combustion doesn’t occur properly and the car has to work harder, consuming more fuel.

You could be unknowingly losing a lot of money due to poor mileage. In some cases, a faulty catalytic converter may also lower the fuel consumption. While this might sound like a good thing, it actually harms the engine in the long run and can lead to expensive repairs.

2. Higher emissions

Since the primary purpose of a catalytic converter is to reduce emissions, a bad catalytic converter would naturally result in higher emissions than usual.

If your car fails an emission test or records unusually high levels of emission, you should definitely check out the catalytic converter. While you may possibly get your car’s emission tested only once a year, black exhaust smoke is a clear indicator of high emission.

3. Misfiring engine

A clog in the catalytic converter blocks the flow of oxygen to the engine. Without adequate oxygen, the engine cannot combust the fuel properly.

This can stop one or more cylinders from working and cause the engine to misfire. If there’s a misfiring engine, it can cause a fire or lead to other expensive repairs.

4. Rattling noises

If the insides of the honeycomb structure in the cat converter break apart, they can start rattling around. The rattling noise would be especially noticeable when accelerating the car. If you notice such a noise, check if it’s originating from the catalytic converter.

5. Check engine light

The check engine light has a very specific purpose – it alerts you upon detecting any malfunction in your vehicle. It checks for a variety of malfunctions, including faults in the catalytic converter.

However, this also means that the light might turn on due to other issues besides a bad catalytic converter. If you notice that the check engine light is on, get a mechanic to check for the problem or decode the error code yourself if you can.


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What Are the Causes of a cracked catalytic converter?

Your catalytic converter may crack due to various reasons. However, the most common causes of a cracked catalytic converter are:

1. Road damage

Debris from the road can cause severe damage to the cat converter. This happens especially when you drive a low-ground clearance vehicle on off-road terrain. Although the cat converter is generally tough, the materials are still too fragile to withstand road damage.

2. Old age

This is one of the most common and obvious causes of a cracked catalytic converter. The heated gasses entering the component exert immense pressure from the insides.

As the component ages, the material weakens and becomes more susceptible to cracking due to the pressure. However, this problem usually occurs only in cars clocked more than 100,000 miles, or you install an aftermarket converter.

3. Faulty spark plugs

When spark plugs start misfiring or do not spark at all, the fuel in the cylinders doesn’t combust properly. The unburnt fuel enters the catalytic converter, where the heat ignites them.

This can cause the catalytic converter to crack or melt down. The same issue could also occur from unburnt fuel reaching the cat converter due to any other reason.

4. Malfunctioning oxygen sensor

Your car’s oxygen sensor measures the gasses in the exhaust fumes leaving the engine in real-time. It then sends the data to the engine’s computer, which uses this information to determine the correct fuel-to-air ratio.

When the oxygen sensor readings are incorrect, it causes the fuel mixture in the engine cylinders to become too lean or too rich. When the mixture is too rich, it causes express pressure inside the cat converter and results in cracks.

Can you drive with a cracked catalytic converter?

Whether you can drive a car with a cracked catalytic converter depends on the damage. The fact that your catalytic converter is not doing its job won’t stop your car from running.

A vehicle can run indefinitely even without a cat converter. However, a cracked cat converter can potentially lead to other problems. In many cases, this issue causes the engine to shut down completely. If that’s the case, you won’t be able to drive the car until you fix the issue.

However, even if your car is still running, we don’t recommend driving it with a cracked catalytic converter. This is because a damaged cat converter can cause severe backpressure to the engine and other components, resulting in costly repairs.

How much does it cost to fix a cracked catalytic converter?

In most cases, you cannot replace a cracked catalytic converter and have to replace it entirely. However, even if it is possible to weld the cracked parts back together, it would be quite expensive.

Repairing a catalytic converter can cost you anything between USD 500 and USD 2,200. You’ll be able to get a more accurate estimate by getting the cat converter checked by a mechanic, provided that it’s repairable at all.

Is a catalytic converter worth fixing?

Considering the cost of repairing a cracked catalytic converter, it’s simply not worth it. You can possibly get a new catalytic converter within the same price range, with the average cost ranging between USD 400 and USD 2,000.

Naturally, replacing your broken cat converter is much better than repairing it, if both are almost equally expensive. There’s no telling how long your repaired cat converter will work before it cracks again; you’ll be better off with a brand new one.


Thanks to the long lifespan of an average catalytic converter, you won’t have to deal with cracked catalytic converters often. However, if it happens under any condition, you must diagnose the real reason and fix it.

For instance, if the crack is due to a faulty spark plug, the same spark plug could also damage the new cat converter. Replacing a damaged catalytic converter is generally better than repairing it.