Catalytic converters are used in internal combustion engines to reduce harmful carbon monoxide emissions. They also break down nitrogen oxides to nitrogen and oxygen and hydrocarbons into water and carbon dioxide. Catalytic converters accomplish these tasks by causing chemical reactions with the exhaust emissions as they flow through. The catalyst used most often in converters are platinum, rhodium or palladium, as these are very reactive metals. The core of the converter is often ceramic or stainless steel. They are formed like a honeycomb to increase the surface area, which increases the effectiveness of the catalyst. Many problems can arise with catalytic converters, which can affect how the engine runs.
One of the effects of a catalytic converter that isn't operating correctly is an engine running with a rough idle. When you are at a traffic light or sign, you will be able to feel an unusual shaky sensation.
Another symptom of a catalytic converter being damaged is the smell of sulphur when the engine is running. Sulphur odours are similar to the smell of rotten eggs.
The engine loses some function with a damaged catalytic converter. Your gas mileage can decrease as a result.
The engine's power may also be decreased. Slower acceleration and power may be noticeable, especially when going uphill.
A damaged catalytic converter may also cause the engine to run hot, which can in turn cause other damage. The running temperature gauge will show if the engine is running hot.