P0148
P0148-HIGH PRESSURE COMMON RAIL (HPCR) CHECKSUM
For complete wiring diagrams refer to Diagrams/Electrical.
- When Monitored:
While the engine is running.
- Set Condition:
A deviation between the fuel pressure set point and the actual fuel pressure.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. OTHERS DTC'S PRESENT
With the scan tool, read DTCs.
Are any other DTC's present?
Yes
- Repair other DTC's first.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To2
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.
Do you have any fuel leaks or damaged components?
Yes
- Repair the fuel leak.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To3
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.
Do you hear a click from the actuator when you cycle the actuator off with the scan tool?
Yes
- Go To4
No
- Replace the fuel control actuator.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
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
Is the fuel rail pressure reading higher at 2000 RPM than at idle?
Yes
- Go To5
No
- Replace the fuel pressure sensor.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
5. HIGH FUEL PRESSURE
Using the scan tool 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 To6
No
- Go To9
6. CASCADE OVERFLOW VALVE
Perform the no trouble code test "*fuel pump return flow test". Fuel Pump Return Flow Test
Did the fuel injection pump pass the test?
Yes
- Go To7
No
- Replace the Fuel pump.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
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.
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. Powertrain Verification Test
No
- Go To8
8. FUEL RETURN LINE OBSTRUCTION, DAMAGED OR DEBRIS
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. Powertrain Verification Test
No
- Go To9
9. LIFT PUMP FLOW
Perform the no trouble code "*LIFT PUMP FLOW TEST".
Did the Lift pump pass the test?
Yes
- Go To10
No
- Replace the Lift Pump.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
10. PRESSURE LIMITING VALVE
Perform the no trouble code test "*PRESSURE LIMITING VALVE ON THE FUEL RAIL FOR INTERNAL LEAKS". Pressure Limiting Valve Test
Did the pressure limiting valve pass the test procedure?
Yes
- Go To11
No
- Replace the Pressure Limiting Valve.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
11. LEAKING FUEL INJECTORS OR HIGH PRESSURE CONNECTORS
Perform the no trouble test "*INJECTOR RETURN FLOW TEST". 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. Powertrain Verification Test
No
- Go To12
12. HIGH PRESSURE FUEL PUMP
Perform the no trouble code test "*HIGH PRESSURE FUEL PUMP PERFORMANCE TEST". High Pressure Fuel Pump Performance Test
Did the fuel pump pass the high pressure fuel pump performance test?
Yes
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition
No
- Replace the High pressure fuel pump.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test