Diagnostic mode A computer system ' s diagnostic mode was used to ascertain whether or not there were problems or inconsistencies in a starship ' s main systems , including the transporter s . When Miles O ' Brien , Data and Deanna Troi , taken over by Ux - Mal criminals , wanted to make sure that nobody could use the transporter to beam them back to Mab - Bu VI , O ' Brien took the entire transporter array off line and placed the transporter in a diagnostic mode which would take hours to complete its cycle . ( ) Types of diagnostic modes . Level 1 diagnostic . A level 1 diagnostic was a troubleshooting / test series that required taking the associated system off - line . In 2369 , Chief Miles O ' Brien ran a level 1 diagnostic of the runabout ' systems , including the central power linkage s . ( ) The same year , he told Julian Bashir that he was thinking of running a level 1 diagnostic of the phase coil generator s when he was back aboard space station Deep Space 9 . ( ) Later , O ' Brien ordered Neela to run a level 1 diagnostic of the runabout ' s computer interface , after they discovered that Ensign Aquino had been murder ed there . ( ) One of several peculiarities that allowed William T . Riker to discover that his " future " was actually a fabricated reality was noticing that a level 1 diagnostic Geordi La Forge had apparently been running had lasted for more than thirty hours . This displayed an uncharacteristic level of incompetence , as the same diagnostic would have never taken the real La Forge more than four hours to complete . ( ) Level 3 diagnostic . Lieutenant Farrell requested permission from Geordi La Forge to run a level 3 diagnostic on the ' s port plasma relay s , as she had noticed one of the generators was fluctuating . ( ) In 2369 , Commander Benjamin Sisko ordered a quick level 3 diagnostic of the graviton generator because of residual charge readings . ( ) The same year , Chief Miles O ' Brien ran a level 3 sensor sweep through the promenade to detect anomalous readings after he found the program ANA . ( ) Level 4 diagnostic . Locking a starship ' s transporters diagnostic mode , effectively putting it into a diagnostic cycle , would keep any inert matter in the pattern buffer . Ordinarily , inert matter couldonly remain in the pattern buffer for seven minutes before becoming irretrievably lost , but Montgomery Scott was able to reconfigure a transporter aboard the , locking the pattern into a level 4 diagnostic cycle to keep his pattern in the pattern buffer for seventy - five years . His pattern was retrieved with minimal degradation . However , another occupant , Ensign Matt Franklin , was not so lucky , his pattern having degraded beyond all hope of retrieval . ( ) Background information . From the entry " diagnostic " in the , " " Engineering analysis programs used aboard Federation starships , intended to permit automated determination of system performance and identification of any malfunctions . Most key systems had a number of such programs available , ranging from level - 5 diagnostics ( the fastest , most automated ) to level - 1 diagnostics ( the most thorough , but the slowest , requiring the most manual labor ) . " "