How does an electronic control module (ECM) differ from an ECU?

The electronic control module (ECM) is specifically designed to manage engine functions, such as fuel injection, ignition timing, and emissions control. It plays a crucial role in optimizing engine performance and efficiency by processing information from various sensors and making real-time adjustments to the engine's operation. This includes controlling air-fuel mixtures, monitoring vehicle speed, and ensuring that emissions stay within regulatory limits.

In contrast, the term electronic control unit (ECU) is a broader term that encompasses various modules throughout a vehicle, including those that manage systems beyond just the engine, such as transmission, ABS, climate control, and more. While the ECM is a specific type of ECU focused on the engine, there are numerous other ECUs responsible for different vehicle functions.

Understanding this distinction clarifies why the correct answer highlights that the ECM specifically manages engine functions, whereas the ECU can refer to any electronic control unit in the vehicle's architecture.