SUTA stands for "Start Upon Temperature Alarm." A SUTA mission requires quite a bit from the onboard battery. Most other mission setup activities, such as starting, stopping, and other power-consuming activities are provided by the 1-Wire interface except for a SUTA mission. It is most likely that the device has a relatively well-used battery, and it takes a little more power than what the current battery can provide to perform a SUTA mission.