Cummins ISB4.5 CM2150 Fault Code: 1981 PID: SPN: 3936 FMI: 15 Aftertreatment Diesel Particulate Filter System – Data Valid But Above Normal Operating Range – Least Severe Level.

Circuit Description
The engine aftertreatment system monitors the soot load in the aftertreatment diesel particulate filter. Under normal operating conditions, the aftertreatment diesel particulate filter is self-cleaning, where soot is converted to carbon dioxide, nitrogen, and water. Under light load operating conditions, it can be necessary to perform a stationary regeneration of the aftertreatment diesel particulate filter. The soot load in the aftertreatment diesel particulate filter is estimated, using the aftertreatment differential pressure sensor and the calculated soot output of the engine.

Component Location
The aftertreatment diesel particulate filter is located in the exhaust system and is installed by the original equipment manufacturer (OEM). Refer to the OEM service manual.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the engine speed is greater than 500 rpm.

Conditions for Setting the Fault Codes
The engine control module (ECM) detects that the diesel particulate filter is plugged or that the differential pressure across the diesel particulate filter is above the maximum limits.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code
-To validate the repair, 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 differential pressure across the aftertreatment diesel particulate filter has dropped below the maximum severity level and the diagnostic runs and passes.
-The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.
-For On-Board Diagnostics (OBD) engines, the ECM will turn off the MIL after three consecutive trips where 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.

Possible Causes
-The aftertreatment wiring harness connectors may be connected to the wrong aftertreatment temperature sensor.
-The aftertreatment wiring harness or aftertreatment temperature sensor connector pin installation may be incorrect.
-The aftertreatment diesel particulate filter can be plugged with ash.
-The engine has been operating in light load conditions that prevent exhaust gas temperatures from being high enough to actively regenerate the aftertreatment particulate trap.
-An engine malfunction that is elevating the engine smoke output.

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

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing, or intermittent connections.