This document describes an automatic engine locking system for drunken drivers using a microcontroller-based embedded system. The system uses an AT89S52 microcontroller, MQ-3 alcohol detection sensor, buzzer, LCD display, motors and other components. It aims to prevent accidents caused by drunk driving by locking the engine if the sensor detects alcohol on the driver's breath. The system has advantages like automation, safety and low power. Potential applications include use in vehicles and workplaces to detect alcohol consumption. Future enhancements could include GSM and GPS for location and notification.