All HOBO and StowAway data loggers are manufactured using precision components. As long as the data loggers are not damaged or exposed to conditions outside of their operating environment, they should maintain their accuracy for a while.
However, all sensors drift over time and therefore should be tested in a controlled environment on a yearly basis to make sure that they are running within the specifications outlined in the User's Manual. Factory testing for thermocouple data loggers is available. Please contact place of purchase for available options and charges.
Please note that the thermocouple probes, connectors, and wires are warranted for manufacturing defects on receipt only. The total error of the data logger is the combined error of the data logger and the thermocouple probe used in conjunction with it.