Which of the following can indicate a malfunction in a vehicle’s emission control system?

Flashing warning lights on the dashboard are a clear indicator of a potential malfunction in a vehicle’s emission control system. Many modern vehicles are equipped with onboard diagnostic (OBD) systems that monitor various aspects of engine performance and emissions. When the system detects an anomaly, such as issues with sensors or components related to emissions, it triggers a warning light. This could include the check engine light or other indicators specifically designated for emission-related problems. Thus, seeing a flashing warning light should prompt further investigation into the vehicle’s emission system to ensure it is functioning properly and that it complies with environmental regulations.

High fuel efficiency, quiet engine performance, and regular oil changes do not directly correlate with or indicate issues within the emission control system; in fact, they often suggest that the vehicle is operating smoothly. Therefore, they are not reliable indicators of malfunction when assessing emissions controls.