Overview
| CODE | REASON | EFFECT |
| Fault Code: 3878 PID: SPN: 3364 FMI: 2/2 LAMP: Amber SRT: |
The diesel exhaust fluid quality sensor has reported a reading too high or low for the operating conditions.
|
Engine power derate. |
Circuit Description
The DEF quality sensor is a smart device and communicates with the engine electronic control module (ECM) via the J1939 data link. The DEF quality sensor receives power and ground directly from the battery. The sensor performs its own internal diagnostics and reports malfunctions back to the primary engine ECM via the J1939 data link. The DEF quality sensor is used to measure the concentration of the DEF in the tank.
Component Location
The DEF quality sensor is typically mounted in the DEF tank or in-line with the DEF dosing unit supply line. Reference the OEM service manual for a detailed component location view.
Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.
Conditions for Setting the Fault Codes
This fault code is triggered when the DEF quality sensor detects that the internal temperature has exceeded 125°C.
Action Taken When the Fault Code is Active
- The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
- Diesel exhaust fluid injection into the aftertreatment system is disabled.
- Engine torque will be reduced.
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 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.
- 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:
- Malfunctioning Aftertreatment DEF Quality Sensor.
Troubleshooting Summary
Solution: S00000563
Verification
Conditions
- Turn keyswitch OFF.
Action
- Inspect the aftertreatment diesel exhaust fluid in the tank for signs of debris or contamination.
- Use a diesel exhaust fluid refractometer to measure the concentration of the diesel exhaust fluid in the tank.
Specification
- If there are signs of contaminates in the aftertreatment diesel exhaust fluid, then proceed to the Repair section.
Linked Solutions
- None
Repair
- Drain the diesel exhaust fluid tank, clean thoroughly and refill with pure diesel exhaust fluid.
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.
If all steps have been completed and no root cause has been identified, then follow the technical escalation process.