P0148
P0148-HIGH PRESSURE COMMON RAIL (HPCR) CHECKSUMWHEN 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
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. OTHERS DTC'S PRESENT
With the scan tool, read DTCs.
Q: Are any other DTC's present?
YES: Repair other DTC's first. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Go To 2
2. FUEL LEAKS
Ensure that the fuel level is above 15% using the scan tool.
Visually inspect the low and high pressure side of the fuel system for fuel leaks or damaged components.
Q: Do you have any fuel leaks or damaged components?
YES: Repair the fuel leak. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Go To 3
3. FUEL CONTROL ACTUATOR
Check for a mechanically stuck Fuel Control Actuator (FCA). Using the scan tool, actuate the fuel control actuator.
NOTE: The fuel control actuator will only click when cycled off.
Q: Do you hear a click from the actuator when you cycle the actuator off with the scan tool?
YES: Go To 4
NO: Replace the fuel Injector pump. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
4. FUEL PRESSURE SENSOR
Using the scan tool, monitor the fuel pressure reading from the fuel rail pressure sensor at idle and at 2000 RPM.
Q: Is the fuel rail pressure reading higher at 2000 RPM than at idle?
YES: Go To 5
NO: Replace the fuel pressure sensor. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
5. HIGH FUEL PRESSURE
Using the scan tool compare the fuel rail pressure set point with the actual fuel rail pressure.
Q: Is the actual fuel rail pressure higher than the fuel rail pressure set point?
YES: Go To 6
NO: Go To 9
6. CASCADE OVERFLOW VALVE
Perform the no trouble code test 9*fuel pump return flow test 9.
Q: Did the fuel injection pump pass the test?
YES: Go To 7
NO: Replace the Fuel pump. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
7. CHECK VALVE DAMAGED OR BLOCKED
Check the fuel drain line check valve in the rear of the cylinder head for signs of damage, blockage, or debris.
Q: Is the check valve damaged or blocked?
YES: Repair the cause of the damaged or blocked check valve or replace the valve. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Go To 8
8. FUEL RETURN LINE OBSTRUCTION, DAMAGED OR DEBRIS
Check the fuel return lines for signs of obstruction, damage, or debris.
Q: Are the fuel drain lines damaged or blocked?
YES: Repair cause of high fuel drain line restriction. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Go To 9
9. LIFT PUMP FLOW
Perform the no trouble code 9Lift Pump flow test 9.
Q: Did the Lift pump pass the test?
YES: Go To 10
NO: Replace the Lift Pump. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
10. PRESSURE LIMITING VALVE
Perform the no trouble code test 9 Pressure Limiting Valve on the Fuel Rail for internal leaks9.
Q: Did the pressure limiting valve pass the test procedure?
YES: Go To 11
NO: Replace the Pressure Limiting Valve. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
11. LEAKING FUEL INJECTORS OR HIGH PRESSURE CONNECTORS
Perform the no trouble test 9*Injector return flow test 9.
Q: Are any Injectors leaking or high pressure connectors leaking?
YES: Replace or repair the leaking fuel injectors or high pressure connectors. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Go To 12
12. HIGH PRESSURE FUEL PUMP
Perform the no trouble code test 9HIGH PRESSURE FUEL PUMP PERFORMANCE TEST 9.
Q: Did the fuel pump pass the high pressure fuel pump performance test?
YES: Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure).
NO: Replace the High pressure fuel pump. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1