Can Bad Catalytic Converter Cause O2 Sensor to Fail?

Bad catalytic converters can damage your car engine severely. But you are concerned about something else, aren’t you?

You’re asking can bad catalytic converter cause the O2 sensor to fail? 

The short answer is yes. Your bad catalytic converter can cause your oxygen sensors failure. Cat converters are responsible for chemical reactions. When it turns bad, it affects the whole engine reaction chain. Consequently, oxygen sensors get affected.

But wait, that’s not all. There are other converter problems as well. Want to know more about your converters and oxygen sensors? Scroll through!

Can A Clogged-up Converter Affect O2 Sensor?

Yes, it can. Moreover, the major cause of catalytic converters going bad is clogging up. The purpose of a cat converter is to keep the engine clean from exhaust pollutants and gases. 

So, when the converter gets clogged up, the efficiency of your engine will drop significantly. Simply put, the O2 sensor will fail. 

If the problem is not fixed properly, you’re in deep trouble. Because a bad O2 sensor can cause damage to your car. So, try to keep an eye on your converter regularly.

How to Diagnose a Bad Catalytic Converter or Clog up?

So, you have suspicions about your converter clogging up? But don’t know how to diagnose it? 

Don’t worry. Because there are very easy ways to determine any issues with your cat converter. We’ve mentioned them below-

Method 1: Pungent Smell

No one likes the smell of rotten eggs, do we? 

Well, if your converter smells like that, it’s mostly because it has met its demise. The rotten egg-like smell is caused by the sulfur gas contained inside. Sometimes, the gas can come out of the exhaust as well.

This test is very easy to conduct. But the success rate is not exactly 100%. 

Want a more surefire test? Perform O2 sensor reading.

Method 2: O2 Sensor Reading

O2 sensor reading can determine any internal problem within the converter. If the sensor reading is not normal, you are looking at a bad catalytic converter.

Generally, 0.45 volts of voltage is considered normal in the O2 sensors. Anything below 0.45 volts is an indication of having a lean fuel mixture. 

A level too high above 0.45V is also not good. So, try to look for those symptoms if you suspect a cat converter failure.

If you want to test it yourself, we recommend this full-function OBDII sensor. Also, don’t forget about picking an oxygen sensor socket.

Other Converter Problems That Can Cause O2 Sensor Failure

So far, we have talked about causes, symptoms, and methods. They will definitely help to find the condition of your cat converter & O2 sensors. But does it mean there aren’t any more problems to look out for?

Apparently, there are some other issues that you should be aware of. So, why don’t we look at your converter problems that are causing O2 sensor failure?

Ignition Misfire

This problem is more related to the engine. Nonetheless, it can also break your converter and O2 sensors. Ignition misfire is the condition of the engine when it can’t generate enough power.

How would you know about engine misfiring? Look for clogged converters, faulty oxygen sensors, etc. Because those are the most common causes. Even transmission problems like chevy 2007’s are partially related to this complicated issue.


Without knowing the exact cause of the issue, it’s not possible to fix your car. However, you can solve the issue yourself if you know your stuff. Otherwise, it’s best to consult an expert for long-term benefit.

Internal Coolant Leaks

Coolant leaks can be external or internal. Internal coolant leaks are tough because they can quickly mix with your engine oil. As a consequence, your engine can get permanently damaged.

But there’s a catch. If the leak is very small or minor, you don’t need to fix it immediately. However, heavy leaking is something you should not postpone fixing. 

Here’s a video for you to understand how coolant works in a coolant system.


Before going for a fix, be sure about the leak first with a pressure tester. Then, you can add leak-resistant products such as liquid-Al stop leak to your cooling system.

Along with that, try to clean out converter every now and then for better performance. We totally love this converter cleaner and highly recommend it. 

If you still notice leakage, contact a professional to get a permanent solution.

Rust or Physical Damage

Converters use catalysts to stay damage-free in tough conditions. Such as high temperatures or heavy rain. But that does not mean it’s free from rust or corrosions.

The converter sits beneath the car. So, it can take a heavy toll due to debris or road curbs. The converter can also catch on rust if you’re not taking care of your care regularly.


Good maintenance is the key to a car’s longevity. As you know, they perform best when you take care of them. Also, if you are storing your car in a garage, we recommend this car cover.

Rusting is also a concern here. Even your clean gas tank can keep rusting! So, it’s important to remove any rust as soon as possible.

That’s why we recommend using rust protection spray to terminate corrosions. 

However, if you notice any external damage, don’t fret. Try to follow your car’s maintenance instructions to prolong its lifespan. 

Permanent Fix

You may have already guessed it. The only permanent fix is to buy a new cat converter. However, most of those come with at least 8-10 years of warranty. Or, an average of 100,000 mileage per transmission.

When there’s nothing left to do, you can change the converter with a professional’s help. Because without technical knowledge and expertise, you can’t do it yourself. 

Also, you have to consider the price of a new converter. It starts from $500 and goes up to $2000. Thus, think thoroughly before making your decision.

So, that’s all on this converter-related issue!


Will a Clogged Catalytic Converter Cause Loss of Power?

Yes, it will. We can’t stress enough how closely catalytic converter and engine power are related. Your clogged catalytic converter can stop exhaust flow which will cause power loss. An extremely serious condition can shut down the engine.

How to Be Sure If My Catalytic Converter Needs Replacement?

Multiple symptoms can indicate a bad condition of the catalytic converter. The rotten egg smell, or sulfur gas coming from the exhaust are common ones. Upon observing those things, you can be sure of your converter’s replacement.

Can I Drive with Bad O2 Sensor?

Yes, you can if you’re able to start the car engine. But we suggest you don’t do this and fix the bad o2 sensor fast. Because if you don’t, you’ll suffer from safety issues. 

Take Away

So, your concern was, can bad catalytic converter cause o2 sensor to fail?. And the answer is yes, it definitely can. To make things clearer, we also added a few other converter issues.

We hope you won’t face any future complications with your converter and O2 sensors. For your guidance, we are always here.

Feel free to contact us, and good luck!

Robert Lozano

1 thought on “Can Bad Catalytic Converter Cause O2 Sensor to Fail?”

  1. Well done, Robert!

    Another very great post! I loved it!

    It’s what I’m looking for.

    But, people can use an OBD2 scanner to diagnose the converter-related codes. How about adding it as a way to identify the problem?

    And, how about writing another post to answer the question can a bad o2 sensor cause a bad cat converter? I think many readers are interested in this aspect.

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