Diagnostic Trouble Codes (DTCs)

Description

DTCs, when set, indicate that the PCM has detected a malfunction in a particular circuit or system.


Operation

The PCM is programmed with routines or checks that it follows only under prescribed conditions (called Conditions for Running the DTC). When these conditions exist, the PCM checks certain circuits or systems for a malfunction. These checks are called Conditions for Setting the DTC. When the setting conditions are true, a malfunction is indicated and the DTC is stored as failed. Some DTCs alert the driver through the SERVICE ENGINE SOON MIL or a message. Other DTCs don't trigger a driver warning. Refer to the DTC List table in Testing and Inspection / Procedures / Vehicle on-Board Diagnosis / Diagnostic Trouble Code Description for a complete list of PCM DTCs and what driver alerts they trigger. The PCM also saves data and input parameters when most DTCs are set. The saved information is called Freeze Frame and Failure Records.