User guide

AutoEnginuity ScanTool User Guide 15
Using the Software
Diagnostic Trouble Codes
The Diagnostic Trouble Code window is probably the most
important window of AutoEnginuity’s ScanTool software; and it’s
the first window you’ll see for just that reason.
If you are experiencing issues with your vehicle, chances are
you have a Check Engine or Service Engine Soon indicator light
(the OBD-II specification refers to these as MILs—Malfunction
Indicator Lights). The MIL tells the driver that an issue has arisen
that needs attention. The MIL will not always come on when a fault
is first found. The decision to illuminate the vehicle MIL for any
diagnostic trouble code (DTC) is manufacturer-specific, based on
their testing of how each system malfunction affects emissions.
Usually a fault must occur multiple times, in separate drive cycles,
before the vehicle’s computer creates a stored fault and illuminates
the MIL. Severe faults require only one drive cycle to illuminate the
MIL indicator.