What are the Symptoms of a Bad Catalytic Converter?

Catalytic converters are crucial to preventing your car from emitting harmful pollutants. A catalytic converter is located between the engine and the muffler, and its main job is to convert harmful pollutants into gases that are safe to expel from the vehicle. If your vehicle's catalytic converter is bad, it may emit harmful emissions into the environment.

Now that you understand what a catalytic converter does and why it is important, here are 5 symptoms of a bad catalytic converter.

Poor Engine Performance

One of the main signs that your catalytic converter is bad, or beginning to fail, is if your vehicle begins to experience poor engine performance. If your converter becomes clogged, the exhaust flow can be impacted which may decrease engine power and acceleration.

Dark Smoke or Sulfur Smell From the Exhaust

Because the catalytic conveyer's job is to prevent harmful pollutants from coming out of your exhaust, if you experience dark smoke or smell sulfur, it could be a sign that your catalytic converter isn't performing as well as it should. A catalytic conveyor that is working correctly should convert hydrogen sulfide into an odorless gas.

Check Engine Light

The catalytic converter connects to the engine and if there is something wrong with it, your vehicle's check engine light may come on. Anytime your vehicle's check light comes on, be sure to get it checked out!

Rattling Noise

Another common sign of a bad catalytic converter is hearing a rattling noise coming from underneath the vehicle. Sometimes, as a catalytic converter ages, the inside breaks down and causes a rattle that may worsen as time goes on.

Vehicle Failed Emission Test

If your vehicle failed its most recent emission test, the catalytic converter probably is to blame. The catalytic converter is one of the most important parts to controlling your vehicle's emissions.


The signs of a bad catalytic converter include poor engine performance, dark smoke or a surfer smell from the exhaust, check engine light, rattling noise, or a failed vehicle emission test.

If you need catalytic converter repair, give our auto repair shop a call today!

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