Bad Catalytic Converter Symptoms (10 Main Causes)

A car’s catalytic converter is used to help clean up emissions before the exhaust is released into the environment. However, the converter can become faulty over time, causing a host of problems for drivers. Our bad catalytic converter symptoms guide should help you determine which symptoms are caused by a failed catalytic converter and what you might do to fix them.

What Is A Catalytic Converter?

Catalytic converters are devices that remove harmful pollutants from the exhaust of an internal combustion engine. A catalytic converter is a heat-resistant ceramic honeycomb structure coated with precious metal (usually platinum). When exhaust gases pass through the honeycomb, they react with platinum to form harmful compounds that are then converted into harmless gases.

The catalyst in a catalytic converter is usually made from platinum and rhodium, although other metals can be used as well. The catalyst can be made in different shapes depending on the application, but most are made up of a number of tiny ceramic tiles or bricks with each brick connected by small channels.

The main function of a catalytic converter is to reduce harmful emissions from cars and trucks. If a vehicle has a functioning catalytic converter, it will have less pollution in its exhaust fumes than one without one — even if it burns poor quality fuel or has been modified for more power.

How Does A Catalytic Converter Work?

The catalytic converter is a device that converts harmful emissions into less harmful ones. The catalytic converter is located in the exhaust pipe and works by using a chemical reaction to convert harmful gases into carbon dioxide and water vapor.

The catalyst in a catalytic converter is usually made of platinum, which is an expensive metal. Platinum has the property of being able to react with nitrogen oxides, carbon monoxide, and other substances found in exhaust fumes.

The catalytic converter works by using heat from the engine to ignite the reaction between the poisons in the exhaust gas and the chemical coating on the catalytic converter’s surface. The result is harmless nitrogen gas (N2) and water vapor (H2O).

What Causes A Catalytic Converter To Go Bad?

When a catalytic converter goes bad, it can cause problems with your vehicle’s emissions. In some cases, the emissions system may not function properly and you’ll notice a lack of power or an increase in fuel consumption. The catalytic converter works by converting harmful gases into less toxic substances that are released into the atmosphere.

There are several things that can cause a catalytic converter to go bad. Here are some of the most common causes:

Catalytic Converter Plugged Up With Carbon

Carbon deposits can build up inside the converter over time, causing it to fail. This happens if you don’t drive your car frequently enough or if you drive at high speeds for long periods of time without taking any breaks.

Incorrect Assembly Of The Converter 

If something goes wrong during assembly, your catalytic converter could end up facing in the wrong direction or be damaged during shipping because it wasn’t packaged properly by the manufacturer. This could lead to poor performance or failure of the part altogether.

Catalytic Converter Overheating

The catalytic converter is designed to operate at high temperatures. However, if it overheats, it can be damaged or even destroyed. This can happen if you leave the vehicle idle for too long or if you drive with your air conditioning on during hot weather.

Some vehicles have an indicator light that comes on when the engine is overheating and others don’t. If your vehicle doesn’t have one, then you should look for other signs such as steam coming from under the hood or smoke coming from the exhaust pipe.

Incorrect Installation

One of the most common symptoms of catalytic converter failure is incorrect installation. This can happen if your vehicle was serviced by someone who didn’t know what he was doing or if he didn’t use the correct parts in replacement of damaged ones.

Overloading The Vehicle

If you overload your vehicle with too many passengers or cargo, it will put more strain on the engine and exhaust system, which can lead to premature failure of the catalytic converter.

Using The Wrong Grade Of Gasoline

Using higher octane gas than what your car needs can cause damage to your catalytic converter because it burns hotter than regular fuel. If you use too much octane in your vehicle, it may cause carbon deposits and other buildups that could clog up your catalytic converter.

Using Leaded Gasoline

Leaded gasoline was used in cars until the early 1990s and this is one of the main reasons why older vehicles have a higher chance of having damage to their catalytic converters. Leaded gas can cause severe damage to the catalytic converter and will require replacement as soon as possible.

A Faulty Oxygen Sensor

Oxygen sensors are used to measure the amount of oxygen in the exhaust system of your vehicle. If there’s a problem with your oxygen sensors then you may notice problems with your catalytic converter such as it not functioning correctly or even failing completely.

You should get these checked out if you notice any issues with them so they can be replaced if necessary without causing further damage to other parts of your vehicle.

Bad Catalytic Converter Symptoms

Check Engine Light

The check engine light is triggered when sensors detect abnormal conditions in your car’s engine. A faulty catalytic converter can cause this light to illuminate, so if you see that indicator come on after replacing your oxygen sensor and/or spark plugs, it may be time to have your catalytic converter replaced.

Acceleration Lag

A catalytic converter plays a crucial role in reducing emissions from your vehicle’s exhaust system by eliminating harmful substances like carbon monoxide and hydrocarbons.

If your catalytic converter is damaged or clogged, it can’t perform its functions properly. This can lead to acceleration lag, which means it takes longer for the car’s engine to reach top speed after pressing the gas pedal.

High Or Low Fuel Consumption

If you notice that you are using more fuel than usual then this could be an indicator that something isn’t right with your catalytic converter.

A clogged catalytic converter will cause unburned fuel to leak into the exhaust system which causes excess emissions and thus increases fuel consumption and lowers mileage per gallon.

Smell Of Sulfur

When a catalytic converter is going bad, it can start to smell like sulfur. This is due to the presence of unburned fuel in the exhaust system. The sulfur smell is caused by the sulfur in the fuel combining with oxygen in the air and then burning. The catalytic converter does not burn the fuel completely, so when it goes bad, some of it will be left over and burn with an odor similar to sulfur.

Discolored Housing

A catalytic converter that has gone bad will have discolored housing. This is because of deposits from unburned fuel that accumulates on top of the housing and then begin to rust when exposed to moisture or water vapor.

If you see rust on your catalytic converter housing, this could indicate that it needs replacement soon, as these deposits can build up over time and become progressively worse until they cause serious damage to your vehicle’s exhaust system.

Starting Issues

A bad catalytic converter can make starting difficult by causing extra emissions and poor engine performance during cranking. This can lead to a hard start or even a no-start situation if you have an older car that uses carburetors instead of fuel injection.

Increased Emissions

When a catalytic converter becomes damaged or fails, it can cause more pollutants to escape into the atmosphere through the exhaust system and produce an unpleasant odor. Some people describe this smell as similar to rotten eggs or burnt rubber.

Engine Misfires

A damaged catalytic converter can cause your engine to misfire, which will cause your car to vibrate or shake when you accelerate from a stop or go up hills. A misfire may also trigger an engine light on the dashboard of your car or truck.

Rattles Or Other Noises

If your vehicle has a rattling noise coming from under the hood when you accelerate or decelerate, then it could be caused by a damaged catalytic converter. This rattling noise is typically heard during acceleration and deceleration because of the increased exhaust flow when these two events occur in an internal combustion engine.

Holes In The Catalytic Converter

Another sign that there could be something wrong with your catalytic converter is if there are holes in it. This will allow exhaust gases to escape from underneath the car instead of going through the system and being filtered out by the converter before they leave through the tailpipe or exhaust pipe. This can make it difficult for your engine to run properly and will cause emissions levels to increase significantly as well.

What Could Damage A Catalytic Converter?

If you have a catalytic converter in your car, it’s important that you know how to take care of it so that it lasts for as long as possible. Catalytic converters can be damaged by:

Extreme Heat

Catalytic converters are made from precious metals, so they can be damaged by extreme temperatures. Excessive heat can cause cracks in the metal and allow exhaust fumes to leak out into your engine compartment.

Excessive Pressure

Too much pressure on the catalytic converter can cause it to crack or break apart altogether, allowing more exhaust fumes into your engine compartment than normal. This is why it’s important to have a proper tune-up performed regularly and not wait until something breaks before getting it fixed.

High Temperatures

Excessive heat can cause the glue holding together the ceramic honeycomb structure to break down, which will reduce the efficiency of your catalytic converter and shorten its life span.

Catalytic Converter Location

The catalytic converter is an important part of your car’s emissions system. It reduces the number of pollutants released from the exhaust pipe into the air. A damaged or clogged catalytic converter will increase pollution levels and hurt your fuel economy.

The catalytic converter is a metal canister attached to the exhaust manifold of the car. The converter contains a honeycomb-like ceramic core coated with platinum and rhodium. These precious metals help convert harmful emissions into less toxic substances by breaking down hydrocarbons into carbon dioxide and water vapor.

If you have noticed that your car is running poorly or that it emits a burning smell, then there may be something wrong with your catalytic converter.

The location of the catalytic converter varies depending on what type of car you drive and whether it has front-wheel drive or rear-wheel drive.

Catalytic Converter Replacement

Catalytic converters are a significant part of your vehicle’s exhaust system. They’re designed to help reduce harmful emissions released by the engine, but they also have other functions, including reducing noise and increasing fuel efficiency.

If your catalytic converter is damaged or broken, you should have it replaced as soon as possible. The longer you wait, the worse it can get. If you don’t take care of your car’s exhaust system, it could result in more expensive repairs in the future.

A damaged catalytic converter can cause problems with your vehicle’s emissions system, leading to an unsafe and illegal driving experience. Catalytic converters also play an important role in reducing pollution in our communities.

The sooner you replace your catalytic converter after damage occurs, the less likely it will be that further damage will occur to other components within your vehicle’s exhaust system or engine itself.


Can A Bad Catalytic Converter Ruin Your Engine?

You may have heard a story about someone who had a bad catalytic converter and their engine was ruined. This is a common misconception.

A catalytic converter does not cause engine failure in any way. It is simply one part of an emissions control system, which helps reduce the number of pollutants produced by your car’s engine.

So, if you are starting to experience problems with your car, don’t automatically blame it on your catalytic converter. It may be something else entirely, like a faulty oxygen sensor or even old spark plugs that need replacing.

What Is The Average Life Of A Catalytic Converter?

The average life of a catalytic converter is between 5 and 10 years. This varies depending on your driving style and the quality of your vehicle’s exhaust system. Some vehicles can last for more than 15 years with proper maintenance.

What Does A Bad Catalytic Converter Sound Like?

A bad catalytic converter will make a hissing sound, much like the sound of air being released from a tire, only more high-pitched and constant. This is due to the fact that the converter is letting unburned fuel through.

If your vehicle has this problem, take it in for service as soon as possible. If you do not have your catalytic converter replaced in time, it can lead to other problems down the road such as engine failure.

How Do You Fix A Catalytic Converter Without Replacing It?

The only way to fix a bad catalytic converter is to replace it with a new one. The process involves removing the old converter from the vehicle and installing a new one in its place. This requires removing the exhaust system from under the hood, unbolting the old converter from its mount, and then attaching it to its new mount point on top of the exhaust manifold. After installation, you must reattach your exhaust system back under your hood by bolting everything back together.


The last thing you want to happen is driving around in your car and finding out that your cat converter is going bad. If you notice any bad catalytic converter symptoms, it’s best to bring your car into a shop sooner than later so they can inspect it. Early detection means less money spent on repairs down the road.

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