Overview
| CODE | REASON | EFFECT |
| Fault Code: 3251 PID: S326 SPN: 4765 FMI: 0/16 LAMP: Red SRT: |
The diesel oxidation catalyst intake temperature sensor reading has exceeded the maximum temperature limit.
|
Progressive power and/or speed derate increasing in severity from time of alert. If the Engine Protection Shutdown feature is enabled, the engine will shut down 30 seconds after the red STOP lamp starts flashing. |
Circuit Description
The aftertreatment temperature sensors are used by the engine control module (ECM) to monitor the engine exhaust temperatures in the aftertreatment system. The aftertreatment temperature sensors are thermistors and change resistance based on the temperature being measured. The ECM provides a 5 volt reference voltage to the sensor. The ECM monitors the change in signal voltage and converts this to a temperature value.
When the exhaust temperature is cold, the sensor or thermistor resistance is high. The ECM signal voltage only pulls down a small amount through the sensor to ground. Therefore, the ECM senses a high signal voltage or low temperature. When the exhaust gas temperature is hot, the sensor resistance is low. The signal voltage pulls down a large amount. Therefore, the ECM senses a low signal voltage, or a high temperature.
Component Location
The aftertreatment diesel oxidation catalyst intake temperature sensor is located in the aftertreatment system. It is located at the intake of the aftertreatment catalyst. Refer to the OEM service manual.
Conditions for Running the Diagnostics
This diagnostic runs continuously when the engine is running and active regeneration of the aftertreatment diesel particulate filter is not occurring.
Conditions for Setting the Fault Codes
The Engine Control Module (ECM) detected the temperature at the diesel oxidation catalyst intake was greater than 687°C [1269°F] for 60 seconds.
Action Taken When the Fault Code is Active
The ECM illuminates the red STOP ENGINE lamp immediately after the diagnostic runs and fails.
A default value for the aftertreatment diesel oxidation catalyst intake temperature sensor reading is used.
Active and stationary regeneration of the diesel particulate filter will be disabled.
The engine will be shut down if the Engine Protection Shutdown feature is enabled.
Conditions for Clearing the Fault Code
- To validate the repair using a Diagnostic Road Test, utilize a route that incorporates both stop and go city type driving and steady state highway type driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.
- To validate the repair using a Chassis Dynamometer, utilize a routine that incorporates acceleration and motoring events, steady state highway type operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.
- 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 red STOP 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
This fault code is logged when the ECM has detected a high temperature condition in the aftertreatment system and active regeneration of the aftertreatment diesel particulate filter is not occurring. The fault code indicates that a secondary fuel source is entering the aftertreatment system and is creating a temperature increase across the aftertreatment diesel oxidation catalyst and/or aftertreatment diesel particulate filter.
Possible causes of this fault code include:
Excessive engine oil or diesel fuel being introduced into the exhaust system from the engine
A damaged engine fuel injector causing unburned diesel fuel to enter the exhaust system
The aftertreatment diesel oxidation catalyst intake temperature sensor malfunctioned in-range
The aftertreatment diesel particulate filter intake temperature sensor malfunctioned in-range
The aftertreatment diesel particulate filter outlet temperature sensor malfunctioned in-range
An in-range engine sensor malfunction has occurred, causing excessive fuel to enter the exhaust system.
The aftertreatment system must be inspected after making the appropriate repair outlined in this fault code troubleshooting tree. Progressive damage to the aftertreatment system may have occurred. Remove the exhaust aftertreatment system from the vehicle to inspect it for potential damage and reuse. Refer to the OEM service manual.
Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.
Troubleshooting Summary
Solution: S00001839
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: 1925, 1963
- Aftertreatment DOC: 3313, 3314, 3315
Linked Solutions
- None
Repair
- Perform a search on the appropriate fault codes.
Validation
- None
Solution: S00008386
Verification
Conditions
- Turn keyswitch OFF.
Specification
- If a leak is found, then proceed to the Repair section.
Linked Solutions
- None
Repair
- Repair or replace the leaking components.
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.
Solution: S00002933
Verification
Conditions
- Turn keyswitch ON.
- Connect the recommended Cummins® electronic service tool or equivalent.
Action
- Compare the ECM code and revision number in the ECM to the calibration revision listed in the ECM calibration revision history for applicable changes.
- Start the engine.
- Allow the engine to reach operating temperature.
- Use the recommended Cummins® electronic service tool or equivalent.
- Perform the Injector Performance Test.
If the Fuel Injector Performance Test will not activate, then troubleshoot Fuel Injector Performance Test Will not Activate.
If the Fuel Injector Performance Test will not complete, then troubleshoot Fuel Injector Performance Test Will not Complete.
Specification
- If a Failed indication is displayed by the recommended Cummins® electronic service tool or equivalent for any injector, then that injector is malfunctioning.
Linked Solutions
- None
Repair
- Replace the fuel injector.
- Perform the Snap Acceleration – Aftertreatment Connected Test.
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: S00003332
Verification
Conditions
- Turn keyswitch ON.
- Connect the recommended Cummins® electronic service tool or equivalent.
Action
- Run the engine at idle.
- Perform the Aftertreatment Fuel Injector Leak Test.
Specification
- If the Aftertreatment Fuel Injector Leak Test does not meet specification, then a malfunctioning aftertreatment fuel injector has been detected.
Linked Solutions
- None
Repair
- Clean or replace the aftertreatment fuel injector.
- Perform the Snap Acceleration – Aftertreatment Connected Test.
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: 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.
If all steps have been completed and no root cause has been identified, then follow the technical escalation process.