The operating temperature in an ‘under the hood’ environment ranges from -55°C to 150°C.  With a moving vehicle the liquid can sway when turning or hitting a bump in the road. If the liquid is near the low level sensing point, the sensor may energize creating an alert of a fault condition. During vehicle swaying the alert may come on and then go off repeatedly. A wide hysteresis built into the sensor will prevent this. Once the sensor is activated, it must remain on until brake fluid has been added. Furthermore, like all plug-in electrical connections, the contacts can oxidize or corrode interrupting the electrical connection particularly in the ‘under the hood’ environment. So the sensor must include the ability to let the on-board computer know that the sensor is properly connected to the electrical system.