Fuel Filter Differential Pressure – Data Valid But Above Normal Operating Range – Moderately Severe Level
Overview
| CODE | REASON | EFFECT |
| Fault Code: 2372 PID: P95 SPN: 95 FMI: 0/16 LAMP: Amber SRT: |
Excessive fuel flow restriction to the high pressure fuel pump has been detected.
|
Possible reduced engine performance.
|
 Engine Control Module (ECM)
|
Circuit Description
The engine control module (ECM) monitors engine operating conditions, including the reading of fuel rail pressure, and changes the flow command to either increase (OPEN the fuel pump actuator) or decrease (CLOSE the fuel pump actuator) the fuel supply to the high-pressure pump.
Component Location
There are two fuel filters and several original equipment manufacturer (OEM) supplied components that can impact this fault code. The pressure-side fuel filter is typically mounted directly to the engine, but can also be remote mounted. The suction-side fuel filters and other OEM supplied components are OEM specific. The OEM is required to supply a suction-side filter, and the exact filter location is OEM dependent. 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
Fuel pressure was less than a calibratible value during high fuel flow conditions indicating a fuel inlet restriction.
Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
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 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
Low fuel pressure at rated speed/load indicates a fuel inlet restriction or a plugged pressure-side fuel filter. Possible causes of this fault code include:
A plugged pressure or suction side fuel filter
Collapsed fuel inlet lines
An obstructed suction tube in the fuel tank
Plugged fuel tank vents.
Malfunctioning high-pressure fuel system
Note: The mounting location of the suction side fuel filter will vary by OEM, and can possibly not be in an obvious location.
Troubleshooting Summary
- Engine will not start
- Low pressure fuel system component is malfunctioning
- Fuel Inlet Restriction check
- Air in fuel check
- Fuel filter differential and gear pump pressure check
- Fuel injector return flow check
- Fuel injector isolation test
- Fuel pressure relief valve return flow excessive
- Air in fuel check
- Fuel passage has debris
- ECM calibration revision history check
Verification
Conditions
- Turn keyswitch ON.
Action
- Attempt to start the engine.
Specification
- If the engine will not start, then reset the search to crank no start.
Linked Solutions
- None
Repair
- Reset the search to crank no start.
Validation
- None
Verification
Conditions
- Turn keyswitch OFF.
Action
- Visually check fuel tank for adequate fuel supply.
Refer to OEM Service Manual
- Visually inspect the engine fuel supply lines for signs of kinks, damage or fuel leaks.
Specification
- If no damage or leaks are observed, then proceed to the Linked Solutions section.
- If there is any damage or leaks found in the OEM fuel system, then proceed to the Repair section.
Linked Solutions
- Fuel Inlet Restriction check
- Air in fuel check
- Fuel filter differential and gear pump pressure check
Repair
- Repair or replace the OEM fuel lines.
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
- Measure the fuel inlet restriction.
Specification
- If the engine will not start, then proceed to the next solution.
If the inlet restriction is excessive, look for the root cause:
Inspect the following components if applicable:
- Suction side fuel filters plugged.
- Fuel heater restricted.
Refer to OEM Service Manual
- OEM fuel lines restricted.
Refer to OEM Service Manual
- ECM cooling plate plugged.
- ECM cooling plate check valve restricted.
- Fuel tank stand pipes restricted.
Refer to OEM Service Manual
Linked Solutions
- None
Repair
Repair or replace only the components that were found to be out of specification.
- Replace fuel filter.
Refer to OEM Service Manual
- Repair or replace the fuel heater.
Refer to OEM Service Manual
- Repair or replace the OEM fuel lines.
Refer to OEM Service Manual
- Repair or replace the ECM cooling plate.
Repair or replace the ECM cooling plate check valve.
- Repair or replace the fuel tank stand pipe.
Validation
- 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.
- Verify adequate fuel level in the tank
Action
- Allow the engine to reach operating temperature.
- If engine will not start, then perform the check during cranking.
- Inspect for air being ingested into the fuel.
Specification
- If air is present in the fuel flow, then a damaged fuel supply line, loose or damaged fuel filter, or a loose connection has been detected.
Linked Solutions
- None
Repair
- Tighten the loose fitting or replace the damaged component that allows air to enter the fuel system.
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
- Perform the Fuel Filter Restriction Test.
- Perform the fuel pump gear pump pressure check.
Specification
- If the pressure is not within specification at the fuel filter head inlet, then a malfunction of the fuel pump gear pump has been detected.
- If pressure from the fuel pump gear pump is within specification and the differential pressure does not meet specification a plugged or blocked fuel filter has been detected.
Linked Solutions
- None
Repair
Repair or replace only the components that were found to be out of specification.
- Replace fuel filter.
- Replace the fuel pump gear pump.
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 High-Pressure Injector Return Flow Test.
Specification
- If the High-Pressure Injector Return Flow Test is out of specification, then tighten the fuel injector connector nuts and perform the High-Pressure Injector Return Flow Test again.
- If the High-Pressure Injector Return Flow Test is still out of specification, then proceed to the Linked Solutions section.
Linked Solutions
- Fuel injector isolation test
Repair
- Check the torque on the fuel connector retaining nuts and tighten if necessary.
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.
- Perform the High-Pressure Injector Return Flow Isolation Test.
Specification
- If the Fuel Injector Return Flow Isolation Test identifies a fuel injector that does not meet specification, then a malfunctioning fuel injector has been detected.
Linked Solutions
- None
Repair
Repair or replace only the components that were found to be out of specification.
- Replace the fuel injector.
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 Fuel Pressure Relief Valve Return Flow Test.
Specification
- If the fuel rail return flow does not meet the specification at the fuel rail pressure relief valve, then a malfunctioning fuel rail relief valve has been detected.
Linked Solutions
- None
Repair
- Replace the fuel pressure relief valve.
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
- Verify adequate fuel level in the tank.
Refer to OEM Service Manual
- Inspect for air being ingested into the fuel.
Specification
- If air is present in the fuel flow, then a damaged fuel supply line, loose or damaged fuel filter, or a loose connection has been detected.
Linked Solutions
- None
Repair
Repair or replace the following components if they are found out of specification:
- Tighten the loose fitting or replace the damaged component that allows air to enter the fuel system.
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
- Remove the pump head fuel inlet banjo bolt.
- Inspect the filter inside the banjo bolt for debris.
Specification
- If debris is found, then proceed to the Repair section.
Linked Solutions
- None
Repair
- Replace the banjo bolt.
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.
If all steps have been completed and no root cause has been identified, then follow the technical escalation process.