Nowadays consuming alcohol and driving is the leading cause of many road accidents. The driving person is not in stable condition so the driving is also inconvenient for the other drivers and it is also question to damage of life of person, property and for others too. In this project, we are developing a system that will automatically lock the engine whenever it senses the person is drunk. The input for the system is in the form of a sensor i.e alcohol sensor which is attached to the controller. Our proposed system would be constantly monitoring the driver’s breath by placing it on the driver steering or somewhere the driver's breath can be constantly monitored by it. So if the driver is drunk and tried to drive, the system detects alcohol presence in his/her breath and locks the engine so that the vehicle fails to start. In another case, if the driver is not drunk while he starts the vehicle and the engine is started but he/she drinks while driving, the sensor still able to detect alcohol in his breath and stops the engine so that the car would not further accelerate and the driver can steer it to the roadside. In this project, we have used an Arduino microcontroller interfaced with an alcohol sensor and a dc motor to demonstrate the working of this project.