If the
coolant reservoir becomes cracked or empty, the coolant level warning light will illuminate on the instrument cluster, alerting the driver that the coolant system is low on engine coolant. This is because the coolant level sensor is inside the coolant reservoir, so when the reservoir is empty, the sensor records coolant absence, and transmits it to the vehicle's computer. In the event of a cracked reservoir, there will be a very noticeable
coolant leak on the ground, underneath the front of the vehicle.