An engine control unit (ECU) is a crucial component in modern vehicles that manages the engine's performance. It uses various sensors to monitor parameters like temperature, air intake, and fuel levels, adjusting the engine's operation for optimal efficiency and power. The ECU processes data in real-time, ensuring that the engine runs smoothly while minimizing emissions. By controlling functions such as fuel injection and ignition timing, the ECU plays a vital role in enhancing fuel economy and overall vehicle performance.