P0148 HIGH PRESSURE COMMON RAIL (HPCR) CHECKSUM

When Monitored and Set Condition:

When Monitored: While the engine is running.
Set Condition: A deviation between the fuel pressure set point and the actual fuel pressure.

POSSIBLE CAUSES

• OTHERS DTC'S PRESENT
• FUEL LEAKS
• FUEL CONTROL ACTUATOR
• FUEL PRESSURE SENSOR
• CASCADE OVERFLOW VALVE
• CHECK VALVE DAMAGED OR BLOCKED
• FUEL RETURN LINES OBSTRUCTION, DAMAGE, OR DEBRIS.
• LIFT PUMP FLOW
• AIR IN FUEL SYSTEM
• LEAKING FUEL INJECTORS OR HIGH PRESSURE CONNECTORS
• PRESSURE LIMITING VALVE
• HIGH PRESSURE FUEL PUMP
• INTERMITTENT CONDITION

DIAGNOSTIC PROCEDURE

NOTE: Refer to VERIFICATION TESTS for appropriate verification test procedures.

1. With the DRBIII®, read DTCs. Are any other DTCs present?
   Yes --> Repair other DTCs first. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 2
2. Ensure that the fuel level is above 15% using the DRBIII®. Visually inspect the low and high pressure side of the fuel system for fuel leaks or damaged components. Do you have any fuel leaks or damaged components?
   Yes --> Repair the fuel leak. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 3
3. Check for a mechanically stuck Fuel Control Actuator (FCA). Using the DRBIII®, actuate the fuel control actuator. Note: The fuel control actuator will only click when cycled off. Do you hear a click from the actuator when you cycle the actuator off with the DRBIII®?
   Yes --> Go To 4
   No --> Replace the fuel control actuator. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
4. Using the DRBIII®, monitor the fuel pressure reading from the fuel rail pressure sensor at idle and at 2000 RPM Is the fuel rail pressure reading higher at 2000 RPM than at idle?
   Yes --> Go To 5
   No --> Replace the fuel pressure sensor. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
5. Using the DRBIII® compare the fuel rail pressure set point with the actual fuel rail pressure. Is the actual fuel rail pressure higher than the fuel rail pressure set point?
   Yes --> Go To 6
   No --> Go To 9
6. Perform the no trouble code test "SYMPTOM: *FUEL PUMP RETURN FLOW TEST". Did the fuel injection pump pass the test?
   Yes --> Go To 7
   No --> Replace the Fuel pump. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
7. Check the fuel drain line check valve in the rear of the cylinder head for signs of damage, blockage, or debris. Is the check valve damaged or blocked?
   Yes --> Repair the cause of the damaged or blocked check valve or replace the valve. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 8
8. Check the fuel return lines for signs of obstruction, damage, or debris. Are the fuel drain lines damaged or blocked?
   Yes --> Repair cause of high fuel drain line restriction. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 9
9. Perform the no trouble code "SYMPTOM: *FUEL LIFT PUMP FLOW AND INLET RESTRICTION TEST". Did the Lift pump pass the test?
   Yes --> Go To 10
   No --> Replace the Lift Pump. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
10. Perform the no trouble code test "Fuel system vacuum test". Is there air in the fuel system?
    Yes --> Go To 11
    No --> Repair cause of air in fuel system. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
11. Perform the no trouble code test "SYMPTOM: *CHECKING PRESSURE LIMITING VALVE ON THE FUEL RAIL FOR INTERNAL LEAKS". Did the pressure limiting valve pass the test procedure?
    Yes --> Go To 12
    No --> Replace the Pressure Limiting Valve. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
12. Perform the no trouble test "SYMPTOM: *INJECTOR RETURN FLOW TEST". Are any Injectors leaking or high pressure connectors leaking?
    Yes --> Replace or repair the leaking fuel injectors or high pressure connectors. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
    No --> Go To 13
13. Perform the no trouble code test "SYMPTOM: *HIGH PRESSURE FUEL PUMP PERFORMANCE TEST" Did the fuel pump pass the high pressure fuel pump performance test?
    Yes --> Refer to the SYMPTOM: INTERMITTENT CONDITION Symptom (Diagnostic Procedure). Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
    No --> Replace the High pressure fuel pump. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).