Circuit DescriptionThe OEM truck manufacturer can install a permit switch in the dash or send an inhibit message via the J1939 data link to the engine ECM. The function of the inhibit message is to prevent the aftertreatment system from performing mobile regenerations.

Component LocationThe aftertreatment diesel particulate filter is located in the exhaust system and is installed by the original equipment manufacturer (OEM). The permit switch can be an actual switch in the vehicle dash or it can be a J1939 message sent via the J1939 data link. Refer to the OEM service manual.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault CodesThe Engine Control Module (ECM) detected the aftertreatment diesel particulate filter regeneration permit switch was disabling regeneration while the ECM was requesting active regeneration of the aftertreatment diesel particulate filter.

Action Taken When the Fault Code is ActiveThe ECM logs the fault code immediately when the diagnostic runs and fails.Conditions for Clearing the Fault CodeTo validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop TalkIf this fault code is active and there has been damage to the aftertreatment system, the permit switch can possibly have prevented the aftertreatment system from performing a mobile (active) regeneration.

Consult with the OEM if the aftertreatment system has malfunctioned due to the permit switch.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

Possible Cause:1) ECM calibration