Ship Diagnostics:

Diagnostic: Engineering analysis programs used aboard Federation vessels intended to permit automated determination of any malfunctions.
Most key systems have 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, which requires an amount of manual labor).

Level 5:
Extremely quick superficial general maintenance scan. Time: 5 -10 Seconds Note: The system being tested can operate under Yellow and Red Alert

Level 4:
A little slower, more of a complete scan. Normally used during a shift change in order to generate an accurate report for the duty officer. Time: 30 Seconds to 1 Minute Note: The system in question is to remain on-line during this test.

Level 3:
Very complete scan. This scan is used on computer systems only Time: 2 - 10 minutes Note: The system in question can remain on-line during this test.

Level 2:
This is a combination of a computer scans which must then be verified by an engineer. Not an exhaustive scan and it is subject to errors Time: 1.5 - 2 hours Note: The system in question should be shut down before this test can be preformed.

Level 1:
The most comprehensive diagnostic. Extremely through computer diagnostic all followed up by an engineering. Exhaustive testing. Time: 2 - 3 hours Note: The system in question must be offline during this test.