Overview
| CODE | REASON | EFFECT |
| Fault Code: 7894 PID: SPN: 3246 FMI: 10/10 LAMP: Amber SRT: |
The aftertreatment diesel particulate filter outlet temperature is not changing with engine operating conditions.
|
Possible reduced engine performance. |
Circuit Description
The aftertreatment exhaust gas temperature sensor module is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment exhaust gas temperature sensor module performs its own internal diagnostics and reports malfunctions back to the engine control module using the J1939 data link. The aftertreatment exhaust gas temperature sensor module is used to measure the aftertreatment diesel oxidation catalyst intake temperature, aftertreatment diesel particulate filter intake temperature, aftertreatment diesel particulate filter outlet temperature, and aftertreatment SCR outlet temperature. The temperature probes are permanently attached to the aftertreatment exhaust gas temperature sensor module and can not be replaced individually.
Component Location
The aftertreatment diesel particulate filter outlet temperature sensor is located in the aftertreatment system. It is located at the outlet of the aftertreatment diesel particulate filter. Refer to the original equipment manufacturer (OEM) service manual.
Conditions for Running the Diagnostics
The engine must be turned OFF for period of 8 hours before this diagnostic will run. This diagnostic runs when the keyswitch is turned to the ON position after an 8 hour cold soak.
Conditions for Setting the Fault Codes
The Engine Control Module (ECM) detected the aftertreatment diesel particulate filter outlet temperature sensor reading was higher or lower than the other temperature sensors on the engine after an extended period of engine off time.
Action Taken When the Fault Code is Active
- The ECM illuminates the amber CHECK ENGINE lamp and/or malfunction indicator lamp (MIL) after the diagnostic fails on two consecutive trips.
- A default value for the aftertreatment diesel particulate filter outlet temperature sensor reading is used.
- Diesel exhaust fluid injection into the aftertreatment system is 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, the engine must be shut down with the keyswitch in the OFF position for 8 hours. After the 8 hour cold soak turn the keyswitch to the ON position for 30 seconds.
- 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:
A malfunctioning aftertreatment diesel particulate filter intake temperature sensor
A malfunctioning aftertreatment diesel particulate filter outlet temperature sensor
Build up or plugging on the inlet face of the Diesel Particulate Filter.
- 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.
Troubleshooting Summary
Solution: S00000280
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 fuel: 1932
- Aftertreatment DPF: 4151, 4158, 4161, 4162, 4163, 4259
Linked Solutions
- None
Repair
- Perform a search on the appropriate fault codes.
Validation
- None
Solution: S00000338
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.
Solution: S00000655
Verification
Conditions
- Turn keyswitch OFF.
- Remove the exhaust piping from the turbocharger outlet.
Action
- Inspect for any fluids.
- Visually inspect the turbocharger exhaust outlet for signs of oil or fuel.
- Perform the Snap Acceleration Test – Aftertreatment Disconnected.
Specification
- If lubricating engine oil contamination is found in the turbocharger exhaust outlet, then reset the search to oil consumption internal.
- 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
- None
Solution: S00000761
Verification
Conditions
- Turn keyswitch OFF.
Action
- Visually inspect for the presence of the aftertreatment DOC.
- Inspect the inlet face of the aftertreatment DOC for reuse.
Refer to Service Bulletin 4021600
- Inspect for cracks in the aftertreatment DOC cell walls.
Refer to Service Bulletin 4021600
- Inspect for soot or oil plugging the front face of the catalyst
Specification
- If plugging or damage is found, then proceed to the Repair section.
- If the face of the aftertreatment diesel oxidation catalyst is cracked or damaged, then proceed to Repair section.
Linked Solutions
- None
Repair
Repair or replace only the components that were found to be out of specification.
- If the face of the aftertreatment DOC is plugged, then clean the aftertreatment DOC.
- If the face of the aftertreatment DOC is cracked or damaged, then replace the aftertreatment DOC.
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: S00009782
Verification
Conditions
- Turn keyswitch OFF.
Action
- Use the recommended Cummins® electronic service tool or equivalent to read the fault codes.
Specification
- If the fault code is active or inactive and has more than one inactive count within the last 25 engine operating hours, then a malfunctioning aftertreatment exhaust gas temperature sensor module 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.
If all steps have been completed and no root cause has been identified, then follow the technical escalation process.