A Nimble array has one temperature sensor in each controller and two on the backplane, for a total of four. A Nimble expansion shelf has two temperature sensors on the backplane. These sensors monitor the ambient temperatures inside the chassis. When a sensor detects temperature of 43oC (109°F) it causes an alert message to warn the user that the system (array or expansion shelf) is running too hot. When a sensor detects temperature of 50oC (122°F), the controller shuts down the system.