The catalytic converter is an essential component of your vehicle’s exhaust system, used to filter out pollutants created during the combustion process. When a manufacturer places a catalytic converter in your exhaust system, it usually lasts the lifetime of your vehicle.
Because of this, people generally don’t know what’s going on with their vehicles when they begin having catalytic converter problems – they only know something is off. Luckily, when you know what to look for, the signs of a bad catalytic converter are easy to spot.
What is a Catalytic Converter?
Before diving into what a bad catalytic converter looks like, it’s important to understand its role. The catalytic converter is part of your vehicle’s exhaust system, converting harmful gases like carbon monoxide, hydrocarbons, and nitrogen oxides into less harmful byproducts such as carbon dioxide and water vapor.
This process helps reduce the pollution emitted by your vehicle, keeping it in line with environmental regulations. The converter contains a honeycomb structure coated with metals like platinum, palladium, and rhodium, which act as catalysts to trigger chemical reactions.
When the converter fails, it can cause a variety of problems, from poor performance to environmental issues.
What Does a Catalytic Converter Do?
Before diving into the problems associated with a bad catalytic converter, it’s important to understand its function. The catalytic converter is located between the engine and the muffler in your vehicle’s exhaust system.
Its main purpose is to reduce harmful emissions by converting toxic gases—such as carbon monoxide, hydrocarbons, and nitrogen oxides—into less harmful substances like carbon dioxide and water vapor.
This conversion is achieved through a chemical reaction facilitated by the precious metals (like platinum, palladium, and rhodium) coated on the converter’s internal honeycomb structure.
When functioning properly, the catalytic converter helps protect the environment and ensures your vehicle meets emissions standards. However, when the converter goes bad, it can lead to a series of performance issues and increase your vehicle’s emissions.
Core purpose of catalytic converters
The core purpose of catalytic converters in automotive systems is to reduce the emission of harmful pollutants from an engine’s exhaust gases and make them more environmentally friendly.
Their effectiveness and reliability are vital not only for maintaining vehicle performance but also for contributing to efforts to reduce atmospheric pollution.
Why Are Catalytic Converters Important?
Before you learn how to tell if your catalytic converter is bad, you should understand what a catalytic converter does and why it has been the vehicle standard for nearly 40 years.
Catalytic converters are comparable to the last line of defense against air pollution from vehicles.
Your catalytic converter is filled with a honeycomb structure of precious metals like palladium, rhodium and platinum that act as a catalyst to filter out harmful contaminants from your exhaust.
If your vehicle runs on gasoline or diesel fuel, your exhaust system regularly releases gases like carbon monoxide, sulfur dioxide, lead, nitrogen dioxide and ground-level ozone.
In the 1970s, people began to understand the harmful effects these gases can have on the environment. Vehicle manufacturers created catalytic converters to break down the unburned gases during the combustion process.
Catalytic converter catalysts reach temperatures up to 800 degrees Fahrenheit and convert toxic gases into safer elements for humans and the environment, like carbon dioxide, oxygen and water.
Why Do Catalytic Converters Fail?
Catalytic converters typically last a long time, but they can still fail due to a variety of reasons. Common causes include:
- Age and Wear: Catalytic converters have a lifespan of around 10 years, depending on driving conditions and maintenance.
- Contamination: Oil or coolant leaks into the engine can contaminate the catalytic converter and damage its internal components.
- Excessive Heat: An engine running too hot can cause the catalytic converter to overheat and fail.
- Misfiring: Engine misfires or incomplete combustion can send unburned fuel into the catalytic converter, causing it to overheat or clog.
- Physical Damage: Road debris or impacts can physically damage the converter’s structure.
Symptoms of Bad Catalytic Converter
The most common symptoms of a bad catalytic converter are a sulfur smell when the engine is warm and a check engine light on your dashboard. You may also notice engine performance issues like acceleration lag, higher or lower fuel consumption, and a misfiring engine.
While these are not all possible symptoms, they are the most common ones. Here is a more detailed list of the signs of a bad or clogged catalytic converter to look for:
#1. Check Engine Light.
The check engine light, one of the most obvious indicators of a malfunction with your car, is also one of the strongest indicators of a bad catalytic converter.
When checked with a compatible OBD scanner, it will show you a catalytic converter-related trouble code that must be decoded with the help of the operating manual.
The most common trouble code when it comes to a bad catalytic converter is the P0420 code.
#2. Acceleration Lag.
If you observe delays when accelerating or a decrease in power when driving in steep areas while all other parts like spark plugs, filters, sensors, etc. are fine, then it could be the catalytic converter that’s bad.
Mechanics often misdiagnose the symptoms of a faulty catalytic converter as being caused by a bad oxygen sensor or any other sensor.
To check if your catalytic converter is clogged, keep your hand close to the exhaust pipe end and ask someone to push the accelerator pedal to increase your car’s RPM to 2000.
If you get a meager amount of exhaust coming out, you might have a clogged catalytic converter. Compare the flow to a similar car if possible.
#3. High or low fuel consumption.
Better or worse gas mileage is one of the symptoms of a poor catalytic converter. While better gas mileage may sound like a good deal, it can damage your engine and may cause even more expensive repairs.
Due to improper combustion of the fuel when the exhaust is clogged, it will make your car engine to be much less efficient and it needs to work harder for the same amount of power.
Therefore, a bad catalytic converter will most often cause a higher fuel consumption, even if lower is possible in some cases.
#4. Smell of sulfur.
When the catalytic converter is clogged, it will restrict the airflow of exhaust fumes so that the engine’s air-fuel mixture will get rich (too much fuel, leading to unburnt fuel).
The combustion of this excessive air-fuel mixture causes a smell like rotten eggs or burnt sulfur, which is an obvious indication of your catalytic converter’s malfunction.
#5. Discolored Housing.
If you see that the catalytic converter’s housing has turned blue or some other color, it could mean that the catalytic converter is clogged and is creating excessive heat.
This could also happen if your engine is not running as it should and unburnt fuel is entering the catalyst. This mixture then ignites in the converter due to the heat and melts its inner material, causing even more blockages.
If your catalytic converter is clogged, it could also create excessive heat inside the engine, which could damage other parts quite quickly. Therefore, you should not drive your car if you suspect that the catalytic converter is bad.
#6. Starting Issues.
If the catalytic converter is clogged, the engine will get too much fuel that the engine cannot burn. It will also create back pressure which will cause the engine to struggle to get rid of the exhaust fumes.
If your car starts for 2-3 seconds and then dies, it could definitely be caused by a clogged converter. This is because it may take 2-3 seconds for the pressure to rise in the exhaust system until the engine is choked and shuts off.
#7. Increased Emissions.
If your catalytic converter is damaged or clogged, there is a risk that the catalytic converter is not doing its job properly anymore.
This will cause an increase in the car engine’s emissions. The overall purpose of the catalytic converter is to remove bad emissions, so this is probably quite obvious.
You will often notice this by seeing dark exhaust smoke coming from your exhaust pipe during acceleration or at idle. If you have a yearly car inspection in the state or country you live in, your car will most likely fail an emission test or smog test.
#8. Engine Misfires.
When the catalytic converter is clogged, it restricts the flow of oxygen in engines, and engines require a lot of oxygen for proper fuel combustion.
This reduced airflow leads to overheating due to an excessive amount of unburned gases and may also lead to a misfiring engine.
If your engine is misfiring, you should get it fixed as soon as possible, because it can lead to further expensive repairs if you just ignore it.
#9. Rattles or other noises.
Inside the catalytic converter, there is a “honeycomb” that can get worn out and this can cause the honeycomb to break apart into pieces. This will cause a rattling noise from the catalytic converter when you rev your car engine.
What could damage a catalytic converter?
Catalytic converters are often getting worn with time and it most likely has to get replaced one or more times during your car’s lifetime.
Some car models even have a service schedule of when it should be replaced (Even if most people don’t follow this because of the expensive replacement cost).
If your car engine is combusting motor oil, caused by worn piston rings or clogged crankcase ventilation, it could cause damages to the catalytic converter really fast. Other causes could be contaminants like unburned fuel caused by misfires.
Coolant entering the combustion chamber by a blown head gasket could also cause damage to the honeycomb.
Catalytic Converter Location
The catalytic converter is located on the exhaust pipe system, between your muffler and the exhaust pipe manifold.
Depending on the car engine, the distance where it’s installed from the engine could differ a lot. On some engines, the catalytic converter is installed directly on the exhaust manifold, while on others it could be installed almost in the middle of the exhaust pipe.
causes of Bad Catalytic Converter
A few things can cause a clogged catalytic converter, inevitably shortening its long but finite lifespan. Let’s explore the most common culprits responsible for clogging your catalytic converter:
#1. Engine Running Rich.
In a relatively newer vehicle, a clogged catalytic converter is often related to a rich fuel/air mixture that allows oil deposits to enter the exhaust system.
Not only does this hamper performance, but it also creates a residue that rapidly traps carbon deposits and other contaminants.
#2. The Engine Running Hot.
The engine running hot due to a fault in the cooling system, a bad EGR valve, or other mechanical faults can also cause a clogged catalytic converter.
Running hot for a long period of time further hampers the performance of the catalytic converter, which accelerates the accumulation of deposits in a car’s catalytic converter.
#3. A Bad Oxygen Sensor.
A bad oxygen sensor can cause a clogged catalytic converter by making the ECU adjust the fuel/air mixture to run rich.
If the oxygen sensor doesn’t cross the threshold for the ECU to throw the check engine light, you can drive for a long time, allowing deposits to build up and eventually clog the catalytic converter.
#4. Animal Debris During Storage.
In an older vehicle or one that’s sat for months in storage, it’s also possible for animal debris to cause a clogged catalytic converter. Even something as simple as a stubborn mouse nest can cause severe catalytic converter problems.
Diagnosing a Bad Catalytic Converter
Diagnosing a clogged catalytic converter can be a bit tricky, but there are several methods you can use to identify this issue. Here’s a step-by-step guide:
- Check for symptoms. As mentioned, common symptoms of a clogged catalytic converter include an illuminated check engine light, trouble starting the car, poor acceleration, a smell of sulfur or rotten eggs, engine misfires, and poor fuel economy.
- Perform a visual inspection. Check the exterior of the catalytic converter for any signs of damage or discoloration. If the converter is glowing red, it may indicate a clog.
- Use an scan tool. Using an OBD-II scanner, read any fault codes that your vehicle’s computer has stored. Codes related to the catalytic converter usually start with P042 or P043.
- Conduct a vacuum test. Connect a vacuum gauge to a vacuum line on the engine. Increase the RPMs slowly. The vacuum should initially drop, then rise and level off. If the vacuum continues to drop, it could indicate the catalytic converter clogged.
- Test exhaust temperatures. Using an infrared thermometer, measure the temperature of the inlet and outlet of the catalytic converter. The outlet should be about 100 degrees Fahrenheit hotter than the inlet if the converter is functioning properly.
How Do You Fix the Bad Catalytic Converter?
As we discussed earlier, your catalytic converter may go bad due to different reasons. If your catalytic converter is bad and you want to fix it, then follow the below-given steps:
#1. Fuel Additives.
One of the simplest methods to fix a clogged catalytic converter is to use a fuel additive. The fuel additive helps your engine run more smoothly and removes carbon deposits from your converter.
For example, if you drive a car that runs on low-octane fuel, switching to higher-octane fuel can fix the issues related to the converter.
#2. Fix the Physical Damage.
Physical damage to the catalytic converter is one of the most common reasons for its failure. Try your best to prevent your converter from damage.
If your converter is damaged physically, you should fix it as soon as possible. If the damage can’t be repaired, you should replace your catalytic converter to prevent the engine from severe damage.
#3. Italian Tune-Up.
An Italian tuning method is utilized to fix many problems on vehicles. You may also fix a bad catalytic converter through this method.
For this method, firstly, you need to push the car hard for the converter to be fully audible. After this, heat your converter to a high temperature between 427°F (427°C) and 1000°C (1832°F).
After heating, drive your car more than normal to burn off carbon deposits accumulated in your intake valves, cylinder heads, oxygen sensors, and catalytic converters. However, this method will not work if your converter is heavily clogged.
#4. Fix Exhaust Issues.
As we discussed above, exhaust leaks are common and may lead to the failure of the catalytic converter and oxygen sensor. Close inspection can reveal an exhaust leak. The repair of the exhaust leak may “restore” the functionality of the catalytic converter.
Corroded hoses and worn exhaust gaskets are the most common problems that are much cheaper and more efficient than replacing your converter. Therefore, you must inspect the exhaust gaskets and engine hoses before replacing the converter.
#5. Catalytic Converter Cleaning.
If your catalytic converter is clogged, you should clean it properly. To clean the catalytic converter, follow the below-given steps:
- Locate the converter. Follow the instructions written in the vehicle manual to locate the converter easily.
- After locating the converter, remove it safely.
- Use a pressure washer to remove any contamination from the matrix.
- Wash the device from both sides.
- After cleaning, wipe the unit with a clean cloth.
- Reinstall the unit and run the engine to check its performance.
What is the average life of a catalytic converter?
The average lifespan of a catalytic converter is roughly ten years or 100,000 miles.
However, there are many factors that can affect the lifespan of a catalytic converter such as the quality of the converter, the type of vehicle it’s in, and how well the vehicle is maintained.
Many catalytic converters will last the life of the car, while others have a scheduled service for when the catalytic converter is to be replaced.
Benefits of Using a Catalytic Converter
A catalytic converter acts as an exhaust emission control unit for reducing toxic gases. Engineer Eugene Hoody invented the first converter in 1950. Catalytic converters work with two types of catalysts, namely, an oxidation catalyst and a reduction catalyst.
Catalytic converters have two major benefits in vehicles. One, it reduces the amount of dangerous pollution produced by the vehicle during the combustion of fuel.
Secondly, it reduces emissions of nitrous oxide by 62%, carbon monoxide by 85%, and hydrocarbon by 87% in the life of a vehicle.
Risks of Ignoring a Bad Catalytic Converter
Ignoring a failing catalytic converter can lead to more significant problems, including:
- Engine Damage : A clogged catalytic converter can cause backpressure in the exhaust system, which puts extra strain on the engine. This can result in engine misfires, overheating, and even total engine failure if the issue is not addressed promptly.
- Failed Emissions Test : A bad catalytic converter can prevent your vehicle from passing an emissions test, which could lead to fines or prevent you from registering your vehicle in areas with strict emissions regulations.
- Increased Pollution : Since the catalytic converter’s job is to reduce harmful emissions, a failing converter will allow more pollutants to be released into the environment. This contributes to air pollution and can harm the environment.
- Costly Repairs : If a bad catalytic converter is ignored for too long, it can cause damage to other parts of the exhaust system and engine, leading to more expensive repairs down the line.
How to Prevent Catalytic Converter Failure
While some catalytic converter failures are inevitable due to aging, there are steps you can take to reduce the risk:
- Perform Regular Maintenance : Regular engine maintenance, such as changing the oil, replacing spark plugs, and keeping air filters clean, can help prevent issues that lead to catalytic converter failure.
- Use High-Quality Fuel : Using high-quality fuel with fewer contaminants can reduce the buildup of residues inside the catalytic converter, helping it last longer.
- Fix Engine Issues Promptly : Address any engine issues, such as misfires or overheating, as soon as they arise. Ignoring these problems can damage the catalytic converter.
- Avoid Short Trips : Frequent short trips can prevent the catalytic converter from reaching the optimal temperature needed to burn off contaminants. Longer drives allow the converter to operate efficiently and reduce the risk of clogging.
how much does cost to Replace Catalytic Converter
The replacement or repair cost of the catalytic converter varies according to the vehicle model, your living area, and the labor cost.
The average replacement cost of the catalytic converter is from $940 to $2470, including parts and labor. The catalytic converter cost itself can be up to $2260 of that.
FAQs.
Q: What Happens When the Catalytic Converter Goes Bad?
The main work of the catalytic converter is to clean emissions from the vehicle and prevent air pollution. A catalytic converter is among the most durable part of a vehicle, but after some time, it can get physically damaged, clogged, or overheated.
A bad catalytic converter causes the check engine light to illuminate, the engine to misfire, and the vehicle may fail to start. Other signs are dark exhaust smoke, the smell of sulfur from the exhaust, and reduced acceleration.
Q: What Does a Bad Catalytic Converter Sound Like?
Disturbing noises when the vehicle is running or idling is a sign that something is wrong with its internal components. A bad catalytic converter produces a rattling noise from below the vehicle.
Excess heat in the catalytic converter can cause the honeycomb structure in the converter to break. The broken parts are what cause the rattling noise. This rattling noise will be more when you start the vehicle, and it becomes worse over time.
Q: How Bad Is It to Drive With a Bad Catalytic Converter?
Most people wonder how dangerous it is driving with a bad catalytic converter. Partially clogged catalytic converters do not affect the vehicle’s drivability, but they will affect your car’s performance.
However, if the converter fails, you may not be able to drive the vehicle. In this case, you will require to have it inspected and replaced immediately. It is prudent to fix issues with the catalytic converter as soon as you find out to prevent further damage.
Q: Will Check Engine Light Come On for Bad Catalytic Converter?
When the check engine light illuminates, it is a sign that something is wrong with the engine parts. A bad catalytic converter triggers the check engine light on.
Some causes of a bad converter that turn the engine light on are broken oxygen sensors or worn-out spark plugs. Therefore if the light turns on, get the vehicle checked by a mechanic to distinguish what the cause is.
Q: How To Know If You Need to Replace the Catalytic Converter?
A failed catalytic converter does not always mean that it needs replacement. At times you can fix the issue by just cleaning the converter.
However, when the issue escalates, you may need to replace the unit. Some of the signs and symptoms that the catalytic converter should be replaced are check engine light on, decreased engine performance, and rattling noises from under the vehicle.
Q: How Long Should a Catalytic Converter Last?
Catalytic converters are designed to last for the lifetime of the vehicle. It is one of the longest-lasting and durable parts of a vehicle. However, due to the excess heat, clogging, and other factors in the system, it may fail.
For how long does a catalytic converter last? This unit can last for at least ten years without issues or around 100,000 miles. However, the time varies greatly depending on the environment you are driving in and your driving style.
Q: Can a Catalytic Converter Cause Shake?
A catalytic converter can become broken due to various factors. When you press the gas pedal, the broken pieces of the converter will produce rattling and vibration noises.
Check for the broken parts of the catalytic converter by shaking it by hand and listening to the noise.
Q: Can a Bad Catalytic Converter Cause Transmission Problems?
When the catalytic converter is clogged, it makes the engine work harder, making it challenging to shift transmissions.
The gears can also have issues if the fuel injection system or fuel filter is dirty or if the engine is too low or too full. The vehicle will have issues accelerating due to the clogged fuel and air filters.
Final Words
A catalytic converter performs a vital role in the vehicle. Its primary function is to convert dangerous emissions produced by the vehicle to less harmful gases.
A vehicle with a good catalytic converter enjoys good acceleration and high fuel economy and passes the emission test.
After learning the symptoms, causes, and how to fix a bad catalytic converter, you should understand how do you check for a bad catalytic converter.
The signs above tell you when it is about to fail. If you notice any of the above signs, have a professional check and fix the vehicle. It is prudent to take the converter for an emissions test every year.