Overview
| CODE | REASON | EFFECT |
| Fault Code: 1981 PID: SPN: 3936 FMI: 0/15 LAMP: Amber SRT: |
The aftertreatment differential pressure has exceeded the maximum operating limits or the diesel particulate filter is plugged.
|
Possible reduced engine performance. |
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 is running.
Conditions for Setting the Fault Codes
The Engine Control Module (ECM) detected the diesel particulate filter is plugged or that the differential pressure across the diesel particulate filter was greater than 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.
Exhaust gas recirculation (EGR) valve operation will be disabled.
Active and stationary regeneration of the diesel particulate filter will be disabled.
Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.
Conditions for Clearing the Fault Code
- To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
- The fault code status displayed by the recommended Cummins electronic service tool or equivalent will change to INACTIVE immediately after the diagnostic runs and passes.
- The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
- For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
- The “Reset All Faults” command in the recommended Cummins electronic service tool or equivalent can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.
Shop Talk
Possible causes of this fault code include:
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.
Excessive ash in the DPF
Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.
Troubleshooting Summary
- Fault Code 1981 requires that ALL solutions be performed
- Check for primary fault codes
- Technical Service Bulletin is available
- Restricted intake air filter
- Aftertreatment DPF differential pressure sensor tubes plugged
- Aftertreatment DPF differential pressure sensor stuck in-range
- Air Handling Performance Test
- Aftertreatment DPF partially obstructed or plugged
- ECM calibration revision history check
- Stationary aftertreatment regeneration is needed
Solution: S00000645
Verification
Conditions
- Turn keyswitch OFF.
Action
- This solution is information only.
- ALL solutions displayed for this fault code must be performed.
- Continue to perform the verifications of ALL solution steps listed for this fault code regardless if a given solution is within specification or out of specification.
- If redirected in this troubleshooting to another fault code or symptom it is required to come back to this fault code troubleshooting and complete every step.
Specification
- This solution is information only.
Linked Solutions
- None
Repair
- If a resolution is found in any solution for this fault code, continue performing ALL solutions listed for this fault code.
Validation
- None
Solution: S00001124
Verification
Conditions
- Turn keyswitch ON.
- Connect the recommended Cummins® electronic service tool or equivalent.
Action
- Use the recommended Cummins® electronic service tool or equivalent to read the fault codes.
Specification
Before troubleshooting this fault code, troubleshoot any fault code that is active or has more than one inactive count within the last 25 engine operating hours from the following list:
- Aftertreatment regeneration: 3375, 3376, 5383
- Aftertreatment differential pressure: 1879, 1881, 1883
- Aftertreatment DOC: 3313, 3314, 3315
- Aftertreatment DPF: 3133, 3134, 3135, 3316, 3317, 3318, 3319, 3321, 3322
Linked Solutions
- None
Repair
- Perform a search on the appropriate fault codes.
Validation
- None
Solution: S00011076
Verification
Conditions
- Turn keyswitch OFF.
Specification
- Proceed to the Repair section if the Technical Service Bulletin is applicable.
Linked Solutions
- None
Repair
- Complete the action outlined in the Technical Service Bulletin.
Validation
- Connect all components
- Connect the recommended Cummins® electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins® electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Solution: S00000025
Verification
Conditions
- Turn keyswitch OFF.
Action
- Visually inspect the air filter to make sure it is not plugged.
Specification
- If the intake air filter is plugged, then a restricted intake air filter has been detected.
Linked Solutions
- None
Validation
- Connect all components
- Connect the recommended Cummins® electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins® electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Solution: S00001183
Verification
Conditions
- Turn keyswitch OFF.
Action
- Inspect the aftertreatment DPF differential pressure sensor tubes for signs of damage, plugging, kinks, leakage or loose connections.
Specification
- If plugging or damage is found, then proceed to the Repair section.
Linked Solutions
- None
Validation
- Connect all components
- Connect the recommended Cummins® electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins® electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Solution: S00000793
Verification
Conditions
- Turn keyswitch ON.
- Connect the recommended Cummins® electronic service tool or equivalent.
Action
- Use the recommended Cummins® electronic service tool or equivalent.
- Monitor the aftertreatment DPF differential pressure sensor voltage.
Specification
- If the aftertreatment DPF differential pressure sensor voltage readings are not within specification, then a malfunctioning aftertreatment DPF differential pressure sensor has been detected.
Linked Solutions
- None
Validation
- Connect all components
- Connect the recommended Cummins® electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins® electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Solution: S00009149
Verification
Conditions
- Reconnect previously disconnected components.
- Turn keyswitch ON.
- Connect the recommended Cummins® electronic service tool or equivalent.
Action
- Use the recommended Cummins® electronic service tool or equivalent.
- Perform the Air Handling Performance Test.
Specification
- If the Air Handling Performance Test does not pass, then reset the search to Air Handling Performance Test Did Not Pass. Only select the solution title that matches the error messages in the recommend Cummins® electronic service tool or equivalent.
- If the Air Handling Performance Test will not start, then reset the search to Air Handling Performance Test Did Not Start.
- If the Air Handling Performance Test does not complete, then reset the search to Air Handling Performance Test Did Not Complete.
Linked Solutions
- None
Repair
- No additional action is required for this solution.
Validation
- None
Solution: S00004187
Verification
Conditions
- Turn keyswitch ON.
- Connect the recommended Cummins® electronic service tool or equivalent.
Action
- If the aftertreatment DPF has already been replaced during this repair, then proceed to the next solution.
- Use the recommended Cummins® electronic service tool or equivalent.
- Perform the Aftertreatment Diesel Particulate Filter Automated Restriction Test.
Specification
- If the Aftertreatment Diesel Particulate Filter Automated Restriction Test exceeds the limits called out in procedure, then a plugged or restricted aftertreatment DPF has been detected.
Linked Solutions
- None
Validation
- Connect all components
- Connect the recommended Cummins® electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins® electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Solution: S00000443
Verification
Conditions
- Connect all components.
- Turn keyswitch ON.
- Connect the recommended Cummins® electronic service tool or equivalent.
Action
- Use the recommended Cummins® electronic service tool or equivalent to read the fault codes.
- Use the recommended Cummins® electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revision listed in the ECM calibration revision history for applicable changes.
Specification
- If a calibration update for this fault code is available, the ECM calibration revision must be that revision or higher.
Linked Solutions
- None
Repair
- Prior to downloading the ECM calibration, check to see that all job images and all other troubleshooting has been documented as downloading an ECM calibration will remove the fault codes on the ECM.
- Download the updated ECM calibration code.
Validation
- Connect all components
- Connect the recommended Cummins® electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins® electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Solution: S00001113
Verification
Conditions
- Turn keyswitch ON.
- Connect the recommended Cummins® electronic service tool or equivalent.
Action
- Perform the Aftertreatment Diesel Particulate Filter regeneration test.
Specification
- If the aftertreatment stationary regeneration does not complete, then reset the Search to stationary regeneration will not complete.
- If the aftertreatment stationary regeneration does not activate, then reset the Search to stationary regeneration will not start.
Linked Solutions
- None
Repair
- No additional action is required for this solution.
Validation
- None
If all steps have been completed and no root cause has been identified, then follow the technical escalation process.