FAULT CODE 1981
Aftertreatment 1 Diesel Particulate Filter System – Data Valid But Above Normal Operating Range – Least Severe Level
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.
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Possible reduced engine performance.
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Aftertreatment Diesel Particulate Filter Differential Pressure Sensor Circuit
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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 INSITE electronic service tool 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 INSITE electronic service tool 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
- Plugged EGR differential pressure sensor supply ports
- Restricted intake air filter
- Aftertreatment DPF differential pressure sensor tubes plugged
- Aftertreatment DPF differential pressure sensor stuck in-range
- Aftertreatment temperature sensor stuck in-range
- Aftertreatment DPF partially obstructed or plugged
- Aftertreatment Diesel Particulate Filter Regeneration Analyzer Test
- Snap acceleration check for excessive black smoke
- ECM calibration revision history check
- Stationary aftertreatment regeneration is needed
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
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
Verification
Conditions
- Turn keyswitch OFF.
Action
- Inspect the EGR differential pressure sensor flow port cross-drillings for soot blockage.
Specification
- If plugging or damage is found, then proceed to the Repair section.
Linked Solutions
- None
Repair
- Remove and clean the EGR mass measurement flow assembly.
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.
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
Repair
- Replace the air filter.
Refer to OEM Service Manual
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.
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
Repair
- Repair or replace DPF differential pressure sensor tubes.
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.
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
Repair
- Replace aftertreatment DPF differential pressure sensor.
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.
Verification
Conditions
- Connect all components.
- Turn keyswitch ON.
- Connect the recommended Cummins electronic service tool or equivalent.
- Start the engine.
Action
- Run the engine at high idle for the following minutes: 10
- Use the recommended Cummins electronic service tool or equivalent.
Monitor the following parameters:
- Aftertreatment diesel oxidation catalyst intake temperature
- Aftertreatment diesel particulate filter intake temperature
- Aftertreatment diesel particulate filter outlet temperature
Specification
- A malfunctioning aftertreatment exhaust gas temperature sensor has been detected if each sensor is not within the following specification of the others: 24 C [43 F]
Linked Solutions
- None
Repair
Repair or replace only the components that were found to be out of specification.
- Replace the aftertreatment exhaust gas temperature sensor module.
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.
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
Repair
- Replace aftertreatment DPF.
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.
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 Aftertreatment Diesel Particulate Filter Regeneration Analyzer Test.
- Verify the recommended Cummins electronic service tool or equivalent has a version that supports this test.
Specification
- If the Aftertreatment Diesel Particulate Filter Regeneration Analyzer Test does not pass, then reset the search to Aftertreatment Diesel Particulate Filter Regeneration Analyzer Did Not Pass. Only select the solution title that matches the error messages in the recommend Cummins electronic service tool or equivalent.
- If the Aftertreatment Diesel Particulate Filter Regeneration Analyzer Test will not start, then reset the search to Aftertreatment Diesel Particulate Filter Regeneration Analyzer Did Not Start.
- If the Aftertreatment Diesel Particulate Filter Regeneration Analyzer Test does not complete, then reset the search to Aftertreatment Diesel Particulate Filter Regeneration Analyzer Did Not Complete.
Linked Solutions
- None
Repair
- No additional action is required for this solution.
Validation
- None
Verification
Conditions
- Engine running.
Action
Verify the hood is closed for vehicles with the air intake system integrated into the hood.
- Perform the Snap Acceleration Test – Aftertreatment Disconnected.
Specification
White smoke during deceleration does not indicate a malfunction.
- If excessive black smoke is detected, then reset the search to black smoke.
Linked Solutions
- None
Repair
- No additional action is required for this solution.
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.
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.
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.