A self-diagnostic was a diagnostic that a machine, system, or android performed on itself to check for errors, usually on a regular basis. Soong-type androids like Data would initiate self-diagnostics at regular intervals to verify that all functions were within established parameters. That same year, after the USS Enterprise-D computer began experiencing a series of malfunctions due to an interface experiment conducted by Data and Geordi La Forge, he stated that he would perform a self-diagnostic. (TNG: "A Fistful of Datas" )