An open door on a storage container or refrigerated truck can lead to problems trying to maintain the correct environment. While a temperature sensor won’t detect an open door, an additional door sensor can be added to monitor this situation, and report it immediately when it has been left open for too long. This door open alert can be sent to a fleet supervisor (either by SMS or through an app for their Android or iOS device) or connected to an in-cab buzzer (for refrigerated trucks).