Children and animals have constantly been forgotten locked inside vehicles and subjected to extreme temperature conditions, which by dozens of times, led them to death. According to statistics compiled by "Kids and Cars", an organization dedicated to prevent child deaths, there were 724 cases of deaths of children caused by asphyxia or by high temperatures in a locked car between 1991 and 2013. This is a worrisome scenario and currently has generated discussion around solutions to the problem. Currently there are ideas and projects seeking for that solution, however they have proved ineffective. This study aims to propose a solution, implementing a system that can assist to the safety of children and animals forgotten in a car. To this end, the system employs a low cost presence sensor, which is ready for reading when the vehicle is turned-off and locked, detecting the presence of a person or animal by an infrared receiver. When the sensor triggers, the system activates the horn and sends a text message to a specified phone number(s) compatible with GSM technology (Global System for Mobile Communications), including the vehicle’s location thru GPS (Global Positioning System). The system in question shows high applicability and low cost, emphasizing that the project represent a very effective security alternative, since it is intrinsic to the vehicle, independent of the driver's attention or memory. Thus, in theory, it is an effective way of preventing more severe outcomes such as those currently taking place.