An engine control unit (ECU) is a crucial component in modern vehicles that manages the engine's performance. It is a type of electronic control unit that monitors various sensors and adjusts parameters such as fuel injection, ignition timing, and air intake to optimize efficiency and reduce emissions. The ECU ensures that the engine operates smoothly under different conditions. The ECU communicates with other systems in the vehicle, including the transmission and exhaust systems, to maintain overall performance. By processing data from sensors like the oxygen sensor and throttle position sensor, the ECU can make real-time adjustments, enhancing both power and fuel economy while ensuring compliance with environmental regulations.