Which of the following is a common symptom of a faulty catalytic converter?

A common symptom of a faulty catalytic converter is poor fuel economy. This occurs because the catalytic converter plays a crucial role in managing exhaust emissions and optimizing the combustion process. When it fails or becomes clogged, it can hinder the flow of exhaust gases, leading to increased back pressure within the engine. This condition can result in inefficient fuel combustion, requiring more fuel to maintain engine performance, which directly negatively impacts fuel economy.

In contrast, increased horsepower, reduced engine noise, and enhanced acceleration are not indicative of a faulty catalytic converter. A malfunctioning catalytic converter generally detracts from engine performance and can lead to a sluggish feel during driving, rather than improved metrics in these areas. Understanding the relationship between the catalytic converter's functionality and fuel efficiency is essential for diagnosing related issues in a vehicle's performance.