(866) 924-4608

We Buy All Cars, Running or Not!

(866) 924-4608 FAST CASH OFFER
Clogged Catalytic Converter Symptoms – Listen For Any Loud Noises Under the Hood! 

Clogged Catalytic Converter Symptoms – Listen For Any Loud Noises Under the Hood! 

The catalytic converter is a key part of the internal workings of your vehicle. Although every single component of your vehicle is important in your car’s performance, the catalytic converter carries out a complex job that is key to your car’s longevity. By noticing and recognizing the clogged catalytic converter symptoms before they get any worse, you can keep repair and replacement costs as low as possible.

Auto Repairs Are EXPENSIVE


Noticing the signs of a clogged catalytic converter, like decreased fuel economy, check engine light, reduced engine performance, and loud noises under the hood, can help drivers get an idea of what they need to fix in their car. 


Diagnosing a clogged catalytic converter typically requires drivers and car owners to notice any smells from their car, recognize any sounds from the converter, or feel for excess vibrations and a rough idle. 


Let’s see the importance of this part in your car, the main function of the converter, signs of a clogged catalytic converter, and the average replacement costs! 

What is a catalytic converter?


When looking into the most concerning clogged catalytic converter symptoms, you need to know this part’s function in your car. A catalytic converter in your car is an exhaust emission control mechanism that reduces toxic gases and pollutants produced in the exhaust gas from an internal combustion engine.


Catalytic converters are used in tandem with the internal combustion engines powered by either gasoline or diesel, depending on the specific make, model, and year of the car.

The Function of the Catalytic Converter

The catalytic converter has to convert three harmful compounds in the car exhaust into compounds that will not destroy your car or the environment. These harmful compounds include hydrocarbons released with the unburned gasoline, carbon monoxide, formed by the combustion of gasoline in your vehicle, and nitrogen oxides, created when the engine’s heat makes the nitrogen in the air combine with the oxygen. 


A catalyst is a substance that accelerates a chemical reaction. Within the catalytic converter, there are two types of catalysts. 

Reduction Catalyst

  • The first is a reduction catalyst, which uses platinum and rhodium to reduce nitrous oxide emissions. 
  • Nitrous oxide is produced by nitrogen oxide and nitrogen dioxide within the exhaust gasses from your internal combustion engine. Without getting rid of these gasses, your car will experience clogged catalytic converter symptoms. 

Oxidation Catalyst

  • The second catalyst type in your catalytic converter is the oxidation catalyst, using platinum and palladium to complete the catalytic converter’s job. 
  • These catalysts burn the carbon monoxide and hydrocarbons that are still located in the incoming gas, helping to rid the smog produced by the unburnt fuel. 


By helping maintain the economy and your car’s lifespan, you can help prevent the clogged catalytic converter symptoms. 

Where is the catalytic converter?

The catalytic converter is located under the exhaust system in the exhaust pipe. Located between the exhaust manifold and the muffler, this part is welded into the exhaust pipe to maintain a secure fit. If you notice the clogged catalytic converter symptoms, you may need to pay for a replacement. In this case, the replacement catalytic converter is typically clamped in place. 

Clogged Catalytic Converter Symptoms

As we know now, your catalytic converter is a huge part of your vehicle. The converter is key to your car’s longevity and lifespan and your vehicle’s overall inner workings by neutralizing hazardous compounds. By doing so, this catalytic converter can cause a huge increase in gas mileage and performance. If you do not take care of your catalytic converter, you will notice the clogged catalytic converter symptoms. 


Catalytic converters are made to last the entire lifetime of your car. Still, without maintenance, these repair issues inside your car and the exhaust system can cause wear and tear.


Driving with a failing or bad catalytic converter can damage your car, hurt the environment due to poor emissions, reduce your fuel mileage, and damage other components of your exhaust system. Preventing these issues from occurring can also help you prevent the clogged catalytic converter symptoms. 


Here are some important signs and symptoms of a failing catalytic converter that can help alert you to the possibility of if a catalytic converter will ruin your engine.

  • Decreased Fuel Economy

Another common result of a failure within the catalytic converter is a decrease in gas mileage, fuel economy, and fuel capabilities. A decrease in fuel efficiency is because your catalytic converter could become clogged over time, filled with debris and rust, and exhaust will become trapped in your car’s engine. 


Suppose your engine starts experiencing a huge increase in gas consumption and is much lower in the mileage per gallon than normal. In this case, you are experiencing one of the most severe clogged catalytic converter symptoms. 

  • Check Engine Light

Your check engine light may illuminate on your dashboard. Although your check engine light can come on for many reasons, this check engine light is one of the first clogged catalytic converter symptoms. Noticing the check engine light before the symptoms get any worse can help reduce the overall repair and replacement prices.


Identifying the root cause of the illuminated check engine light will require a vehicle diagnosis. Finding the dashboard warning’s reason can help you determine if the clogged catalytic converter symptoms will result in complete failure in your car. 


A check engine light can also come on for other reasons, like these possible alternatives compared to your catalytic converter. 

    • Your oxygen sensor could be failing, monitoring the amount of unburnt oxygen in the car’s exhaust system, and sending data to the vehicle’s electronic control module. 
  • Replacing your oxygen sensor costs between $209 and $94 for the parts, while the total procedure is between $113 and $478 for the entire procedure. 
    • The second reason could be a loose fuel cap, which can happen from not tightening the fuel cap after getting gas in your vehicle’s tank. 
  • Replacing the fuel cap in your car costs only around $16 to replace their part, helping turn off the check engine light and prevent the clogged catalytic converter symptoms. 
  • Reduced Engine Performance

If your converter is clogged, the exhaust can build up in your vehicle and reduce the performance, lowering the overall speed, acceleration rate, and power. Clogged catalytic converter symptoms can make it feel like the acceleration is no longer there, even if the car’s gas pedal is working correctly.

  • Noises From Under the Hood

Your catalytic converter is shaped with small components that can cause a rattling sound due to the quick movement when it is broken. If your catalytic converter is damaged or failing, this rattling will be very loud when the car starts or will get worse as you continue driving your vehicle. 


If you hear a rattling noise with the other symptoms on this list, like decreased performance and gas mileage, there is a good likelihood that your catalytic converter is what is at fault. Diagnosing this part can help you prevent clogged catalytic converter symptoms from worsening over time. 

Diagnosing Clogged Catalytic Converter Symptoms

To prevent the clogged catalytic converter symptoms from ruining your engine, you should take note of a few signs that can clue you into the problems occurring in your vehicle. Fixing these issues before they get any more severe can help keep repair and replacement costs as low as possible. 

  • Strong Smell 

If you smell the strong “rotten eggs” coming from your vehicle, this is the easiest way to diagnose the car. Fuel contains a small amount of sulfur, which is usually burned so that it is odorless. However, if the catalytic converter has undergone intense internal damage, the replacement will mean the mechanism is not working properly.

  • Rattling from Converter

In some cases, you can also hear the rattle from the catalytic converter. If you hear this, the converter’s element has become loose and disengaged and can move around during use. If you remove the entire unit, try hitting it with a hard tool to see if you can hear the clatter inside the converter. If you hear any noises, this is one of the main signs of clogged catalytic converter symptoms. 

  • Check the Engine Idle

To cross-check and ensure that you do not have a bad oxygen sensor when you do not see the check engine light, use a vacuum gauge, and connect the gauge to the intake manifold vacuum line. Then, start the engine and let it idle while you temporarily check the gauge’s reading. If you find the engine idle is running rough, this is a sure clogged catalytic converter symptom in your vehicle. 

  • You can tell your vehicle is having a rough idle if there is shaking and bouncing sensation in the vehicle, and you feel like the car is vibrating too much. Although some cases are less severe than others, the rough idle is usually pretty identifiable by both the driver and passengers.
  • You might also notice strange sounds when the car has a rough idle in addition to the vibrations. Along with the strange sounds, there might be an inconsistent engine RPM while you are driving. Typically, a healthy vehicle will have a smooth RPM that stays at a consistent level of around 1,000 revolutions. 
    • If your vehicle is too far below or above this number, you are experiencing clogged catalytic converter symptoms. 

Clogged Catalytic Converter Symptoms – Replacement cost 

To prevent a bad catalytic converter from ruining your engine, you might need to undergo a complete catalytic converter replacement to keep your engine and the parts of your car healthy and lasting longer. So, how much does it cost to replace a catalytic converter? 


Well, this number that you will be looking for depends on a multitude of factors, like your vehicle’s make and model, the quality of the replacement, and labor costs at the specific shop you visit. Once you have the diagnosis, you must add the current market cost of the catalytic converter replacement.

Make and Model of Car

  • The vehicle’s make and model can mean that an older car is going to cost less for a total catalytic converter replacement than a newer vehicle like a 1994 Toyota Camry vs. a newer 2010 Chevrolet Silverado. 
  • In addition, the quality of the replacement unit can affect the overall price and cost. Not all catalytic converters are this high quality or created equal, with some available for under $100, while others can run upwards of $1000.

Labor Costs

  • Furthermore, the labor costs will vary depending on the mechanic shop you visit. Some mechanics will charge you around $70 per hour for their labor costs, while others can go upwards of nearly $130 for an hour of this kind of work. 
  • Also, the time to replace it depends on the kind of car you have, with some jobs taking one hour, and others taking two hours, which will increase the labor cost to fix the clogged catalytic converter symptoms. 

Average Cost for Catalytic Converter Replacement

  • The typical cost of a catalytic converter replacement is usually between $1,000 to $2,500, which is no cheap replacement. 
  • The total replacement cost for catalytic converters is usually between $945 on the low end and $2475 on the extremely high-end for severe damage and luxury cars. 
  • However, to prevent a bad catalytic converter from ruining your engine, this price is what you will have to pay to keep your vehicle healthy to prevent the clogged catalytic converter symptoms. 

The Bottom Line

Figuring out the causes and symptoms of the clogged catalytic converter symptoms will help you keep your car working at a high-performing level for a long period of time without any issues. As we know by now, the catalytic converter is a key part of your vehicle’s internal workings. Although every single component of your vehicle is important in your car’s performance, the catalytic converter carries out a complex job key to your car’s longevity.