Diagnostic Trouble Codes (DTCs) are grouped into several types. Each type has a unique set of characteristics for MIL operation, DTC storage, and DTC clearing. The following list contains a brief summary of the DTC types and the associated properties of each.

Type A

This DTC is emissions related. The MIL illuminates and default actions, if any, are activated immediately after a failure is detected. The DTC is then stored in history and the Freeze Frame data is captured.

Type B

This DTC is emissions related. Default actions, if any, are activated and a Failure Record is stored after the first failure is detected. At the time of the first fail, the DTC will appear in memory as pending. If the next trip reports a pass, the pending DTC is deleted. If the failure recurs on the next consecutive drive cycle, the MIL illuminates, the DTC is stored in history, and the Freeze Frame data is captured at the time of failure.

Type C

This DTC is non-emissions related. The TCM stores the DTC in History and Failure Records during the first trip in which the conditions for setting the DTC are met. The TCM does not store the DTC in Freeze Frame and does not illuminate the MIL. For some type C DTCs, a separate service lamp, other than the MIL, may be illuminated.