What are the Symptoms of a Bad Catalytic Converter?

A catalytic converter is a car component that forms part of the exhaust system. It's a metal canister filled with chemical catalysts (Palladium and Platinum) that help convert vehicle emissions into less harmful gases.

Over time, the converter can get damaged and become faulty. Here are the common symptoms of a bad catalytic converter.

Rattling Noises

These noises usually occur in old and internally damaged catalytic converters. They occur due to the breakaway and collapse of the catalyst meshes lined inside the metal canister.

The damage to the honeycomb mesh stems from the rich fuel mixture from the engine. A rattling noise is easy to hear when you start your car's engine, and it can worsen over time.

Reduced Engine Performance

If the catalytic converter is damaged, you may experience reduced engine performance characterized by the loss of power and acceleration. Another sign is a reduction in fuel economy.

A clogged converter results in the restricted flow of exhaust gases, while a cracked one can cause the leakage of harmful gases when the car is operational. That minimizes the vehicle's efficiency.

The Check Engine Light Turns on

When the engine light on the dashboard turns on, there's a possibility that the catalytic converter is damaged. It can occur when the engine computer detects that the catalytic converter is inefficiently catalyzing the exhaust gases, turning the lights on to alert you of the problem.

It's crucial to schedule vehicle scanning for trouble codes to ascertain the issue. Afterward, the repair technician can give you the way forward.

Rotten Eggs Smell in the Exhaust

It's common when the fuel in your car contains sulfur. The combustion of the sulfur-rich fuel forms hydrogen sulfide that has the characteristic rotten egg smell.

A damaged catalytic converter will not convert the hydrogen sulfide to odorless sulfur dioxide, hence the pungent smell and a dark exhaust smoke when the car is running.

Failed Emission Test

A trouble code will be captured and stored in the engine computer when your car has a damaged and inefficient catalytic converter. If this code pops up during an emission diagnostics test, it's a sign that the vehicle has failed the emission test and the catalytic converter needs replacement.


A functioning catalytic converter is vital to alleviate the dangers posed by the harmful exhaust fumes. If you need catalytic converter repair, call Tri Star Automotive, Inc. today!