Can A Clogged Catalytic Converter Cause A Misfire (Faulty Converter Code)

Can A Clogged Catalytic Converter Cause A Misfire

Engine misfires are often caused by spark plugs and other ignition parts, but sometimes, a misfire can be caused by other reasons, such as a clogged catalytic converter.

Because clogged catalytic converters do not cause misfires often, it can be difficult to determine this issue as the reason behind the misfires.

So, can a clogged catalytic converter cause a misfire? Yes, a clogged catalytic converter can cause a misfire. However, it’s important to note that most misfires are not caused by a clogged catalytic converter. Instead, spark plugs are considered the most common reason for the misfire. It’s important to look at the more common reasons for misfire before checking out your catalytic converter.

This article takes a close look at the role of catalytic converters, what happens if the converter gets clogged, and other potential causes for engine misfires.

Can A Clogged Catalytic Converter Cause A Misfire?

Yes. A clogged catalytic converter can cause a misfire, but a misfire is not the only symptom of a clogged catalectic converter. Similarly, there are other possible reasons behind the engine misfire.

To fully understand how a clogged catalytic converter can cause a misfire in your automobile, let’s learn more about the converter itself.

What Is A Catalytic Converter?                

The purpose of a catalytic converter is to convert harmful compounds found in your vehicle’s emissions into safe compounds, such as steam.

It does this by splitting up the unsafe molecules so that they are released into the air in a safer manner.

In order to do this job, your catalytic converter includes reduction catalysts and oxidation catalysts. The reduction catalysts remove oxygen to reduce nitrogen oxides, whereas oxidation catalysts add oxygen to remove carbon monoxide.

As you may or may not know, both nitrogen oxides and carbon monoxide are dangerous on their own, but the molecules can be broken up to create safer emissions.

Though all catalytic converters serve the same function, there are two main types of converters your vehicle may have: a two-way or three-way.

Many modern engines use the three-way catalytic converter because it also includes the reduction catalyst. Diesel engines, however, use two-way converters.

Read also: What Happens When The Catalytic Converter Goes Bad (Symptoms)

Why Does A Clogged Catalytic Converter Cause A Misfire?

Whenever a catalytic converter gets clogged, the engine will create toxic byproducts, such as hydrocarbons, carbon monoxide, and nitrogen oxides.

Additionally, the clogged catalytic converter forces the car to lose power, making it more difficult for smoke to exit through the car’s exhaust pipe and engine.  

The fact that harmful toxins are being released is not what causes the misfire. It’s simply that there is limited power and smoke cannot leave the car as it should.

Read also: Can a Catalytic Converter Unclog Itself? (Clear a Clogged)

How Does A Catalytic Converter Get Clogged?

Most often, catalytic converters get clogged whenever oil or antifreeze enters the vehicle’s exhaust system.

With the excess oil and antifreeze, a thick layer of carbon and soot coats and clogs the passage in and out of the converter’s catalyst. Two separate problems are created as a result.

Firstly, these deposits prevent the catalytic converter from doing its job of removing harmful emissions.

Secondly, backpressure increases because exhaust flow is restricted. This increased pressure further causes heat and exhaust to go back inside the engine, creating a lot of internal damage.

Read also: How to Clean a Catalytic Converter With Seafoam (Best Tips)

Other Signs Of A Bad Catalytic Converter

If you suspect that a clogged catalytic converter is causing your vehicle to misfire, there are a couple of other signs you can look out for. All of these signs point to a bad catalytic converter in your engine:

Reduced Power When Accelerating

Whenever your catalytic converter is clogged, you will likely experience a loss of power whenever you are driving uphill or accelerating.

Even if you have taken your vehicle to the mechanic for this issue, it can be difficult to diagnose a bad catalytic converter as the cause since the part is partially obstructed.

You can try to determine if the clogged catalytic converter is the cause for this reduction in acceleration power by performing an at-home test.

Have a partner get your vehicle’s RPM between 1800 and 2000. Place your hand behind the tailpipe. The catalytic converter is clogged if you can feel hot exhaust.

More Emissions

Increased emission is one of the most common symptoms of a clogged catalytic converter. Whenever this part is faulty, more gases will be admitted with the exhaust system since it is unable to break apart the molecules properly.

As soon as you notice more carbon emissions exiting your vehicle, you likely have a clogged catalytic converter.

Poor Engine Performance

Because of the backpressure increase, clogged catalytic converters often result in poor engine performance.

Poor engine performance results in symptoms like shaking when driving, sudden pressure outbursts, or even stalling.

Rotten Egg Smell

If your catalytic converter has been clogged for some time, you will likely start smelling an odor similar to rotten eggs. This sulfuric smell comes from poorly converted exhaust gases.

Check Engine Light Is On

Your check engine light can come on for a number of reasons. If you cannot pinpoint why the check engine light is on, the catalytic converter can be the issue.

Take your vehicle to a professional to determine if the check engine light is on due to a clogged catalytic converter.

Other Potential Reasons For An Engine Misfire

As we mentioned above, a clogged catalytic converter is not the most common reason for engine misfires.

Before checking out the converter, it’s better to look at the vehicle parts most likely associated with the misfire issue.

Spark Plugs

Spark plugs are the most common cause of engine misfires. Spark plugs are responsible for delivering the electric current from the ignition to the combustion chamber, allowing the fuel and air mixture to ignite.

Whenever spark plugs are worn, installed incorrectly, or mishandled, a misfire can occur.

Anytime spark plugs are not handled properly, they can leak air, which essentially throws off the ratio between air to fuel. Hence, there is a misfire in the engine.

Carbon Tracking

Carbon tracking, sometimes called flashover, is another common reason engines misfire. Carbon tracking happens whenever oil, erosion, dirt, or moisture ground the spark at the ignition point of the spark plug insulator.

Today, modern spark plugs are designed to prevent this issue, but older vehicles may still face it.

Other Ignition Problems

Spark plugs are considered most likely to blame for any ignition problems and misfires, but there are other potential ignition system problems causing the misfire.

For example, coil packs, crankshaft position sensor, and wiring can all result in an engine misfire.

How To Determine If A Clogged Catalytic Converter Is Causing A Misfire?

Because so many parts can cause an engine misfire, it can be difficult to determine the exact cause. We recommend looking at the spark plugs, carbon tracking, and other ignition parts to rule out the more common causes of the issue first.

After that, you can move on to the catalytic converter. Follow the three steps below to predict and confirm that a clogged catalytic converter is in fact the culprit behind the engine misfires.

Look For Other Signs

Make sure to pay attention to any of the other signs related to a bad catalytic converter.

If the misfires are accompanied by reduced acceleration power, increased emissions, and reduced engine performance, a clogged catalytic converter is likely plaguing your vehicle.

You don’t necessarily have to notice all of the symptoms, but you will most likely notice a couple if your catalytic converter is clogged.

Feel The Exhaust

If you start noticing multiple signs that your catalytic converter is clogged, you can try the hand and exhaust method that we went over briefly above.

So that you don’t have to scroll back up, here is how to do an at-home test to see if your catalytic converter is clogged:

  1. Have a friend help you out.
  2. Have your partner hold the vehicle’s RPM between 1800 and 2000.
  3. While the RPM remains at that range, place your hand directly behind your vehicle’s tailpipe to feel the exhaust flow.
  4. If the exhaust flow feels hot, your catalytic converter is clogged. If it does not feel hot, it either is not clogged enough yet or it is not clogged at all.

Keep in mind that this test does not replace the value of having your vehicle inspected by a professional, but it can help narrow out some potential causes at home.

Take Your Vehicle To A Professional

If you suspect that your catalytic converter is clogged after performing the above test, take your vehicle to a professional.

Only from a mechanical professional can you confirm that a clogged catalytic converter is the issue with your vehicle.

Final Thoughts

To answer the question of this article bluntly, yes. Catalytic converters can cause engine misfires if clogged, but other parts in your vehicle are most likely the cause for the misfires.

By performing a series of tests and taking your vehicle to a professional, you can definitively determine the cause for your engine misfires.

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Jeff is an automotive technician, technical writer, and Managing Editor. He has held a lifelong passion for cars, with a particular interest in cars like the Buick Reatta. Jeff has been creating written and video content about transportation, automotive, electric cars, future vehicles as well as new, used for more than 18 years. Jeff is based in Boulder, Colorado.

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