The ScanGauge II can check for Diagnostic Trouble Codes (DTCs) and if found, can display how many there are and the Trouble Codes themselves.Using the internet or repair manuals, these can be translated to the failed component and repairs can be made.

Data captured when the Trouble Code was set can be recalled to help troubleshoot the problems (was the temperature hot or cold, speed high or low, etc.). The ScanGauge II can be used to clear the trouble codes and data which will turn off the warning (Check Engine, Service Engine soon, etc.) lamp.

Some states now require that vehicle self tests have been completed since the codes were last cleared, before running emissions checks. The ScanGauge reports this "Readiness".