What does it indicate if the check engine light is illuminated?

When the check engine light is illuminated, it signals that the engine control unit (ECU) has detected a fault within the vehicle's engine management system. This light serves as a warning indicator that allows the driver to be aware that there is a potential issue that could affect the vehicle's performance, emissions, or overall reliability.

The ECU continuously monitors various components and systems, such as the engine, fuel system, and exhaust emissions. If it identifies a problem—such as an issue with the fuel mixture, ignition system, or even sensor malfunctions—the check engine light will activate, prompting the driver to seek further investigation or diagnostic testing.

Understanding this relevant aspect of vehicle maintenance is crucial for diagnosing problems early before they escalate into more significant issues. Addressing the underlying faults that trigger the check engine light can lead to improved vehicle performance, fuel efficiency, and emissions compliance.