Home » Symptoms of a Bad or Failing Catalytic Converter

Symptoms of a Bad or Failing Catalytic Converter

First and foremost, you need to know what a catalytic converter is. A catalytic converter is an important car component that works to reduce vehicle emissions and pollution. It is a metal canister that is installed in the exhaust system. It is filled with a chemical catalyst, usually a platinum or palladium mixture, and helps convert the vehicle’s emissions into non-harmful gasses. Usually, a faulty catalytic converter will produc/e one of 5 symptoms that alert the driver that replacement may be required.


Leaking Engine Coolant

Engine Coolant can leak into the combustion system because of a faulty cylinder head gasket, and engine oil. Those fluids can clog a catalytic converter so that exhaust gases are restricted from passing through.



Catalytic converters can overheat because of excessive amounts of unburned gas caused by a misfiring spark plug or a leaky exhaust valve. A failed oxygen sensor can also cause overheating.


Reduced Engine Performance

If your catalytic converter is going bad, then the first thing you will notice is reduced engine performance. Since the catalytic converter is part of the vehicle’s exhaust, it can affect the performance of your engine. A clogged converter will limit the exhaust flow, while a cracked or broken converter will leak harmful toxins. Either way, it will affect your car negatively in acceleration as well as fuel economy.


Rattling Noise

Rattling noises from under the vehicle is another common symptom of a bad catalytic converter. If the converter is old or damaged internally, the excessive internal mixture of fuel and the catalyst can cause breaking which causes the rattle. This rattle will be more obvious when starting the vehicle and will get worse over time.


Sulfur Smell from Exhaust

During engine combustion, sulfur-containing gasoline becomes hydrogen sulfide. A properly working catalytic converter will convert hydrogen sulfide into odorless sulfur dioxide. If your converter starts failing, you will smell a rotten egg-like odor coming from the exhaust. There is also a chance that dark smoke will follow the odor.


Check Engine Light

Modern vehicles monitor the efficiency of the catalytic converter by tracking the gas levels in the exhaust. If the computer detects that the catalytic converter is not working properly, it will turn on the check engine light. Having the vehicle scanned for trouble codes and making sure that it is indeed the converter causing issues is a good way to double check.


Failed Emissions Test

Some states in the U.S. require a diagnostic check of the engine’s computer to pass an emissions test. A trouble code will be stored in the car’s computer if it has a faulty catalytic converter. If the code pops up, the car fails the test.


At Hurricane Automotive, our mission is to supply you with top quality catalytic converters and performance exhaust products for your vehicle from brand names that you can trust. Since the company was founded, we have shipped thousands of catalytic converters and performance exhaust products to satisfied customers throughout the country. If you have more questions or concerns about your catalytic converter, Contact Us. We will be happy to answer all your questions!