Permanent Diagnostic Trouble Code (DTC)

The software stores a permanent DTC in non volatile random access memory (NVRAM) whenever a DTC is set and the MIL has been illuminated. Permanent DTCs can only be cleared by the module strategy itself. After a permanent DTC is stored, 3 consecutive test passed monitoring cycles must complete before the permanent DTC can be erased. At that time, both the permanent DTC is erased and the MIL is extinguished. The PCM clears permanent DTCs after one monitoring cycle if a request to clear DTCs is sent by the scan tool, and the test subsequently runs and passes (test must continue to pass for the entire driving cycle for continuous monitors) and a Permanent DTC Driving Cycle has been completed. A Permanent DTC Driving Cycle requires a total of 10 minutes of engine run time, consisting of 5 minutes of vehicle operation above 40 km/h (25 MPH) and 30 continuous seconds of vehicle operation at idle. After clearing DTCs, running the OBD Drive Cycle ensures that all monitors complete, the Permanent DTC Driving Cycle completes, inspection/maintenance (I/M) readiness codes are set to a ready status and any permanent DTCs are erased. A permanent DTC cannot be erased by clearing the KAM. The intended use of the permanent DTC is to prevent vehicles from passing an in use inspection simply by disconnecting the battery or clearing the DTCs with a scan tool prior to the inspection. The presence of permanent DTCs at an inspection without the MIL illuminated is an indication that a correct repair was not verified by the on board monitoring system.