P0148

P0148-FUEL DELIVERY ERROR

For complete wiring diagrams refer to Diagrams/Electrical.


Theory of Operation

The ECM will turn on the MIL lamp immediately after the diagnostic runs and fails. The ECM will turn off the MIL lamp after the diagnostic runs and passes in 4 consecutive drive cycles.

- 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. SETPOINT VS FUEL PRESSURE

With the scan tool watch fuel pressure vs. setpoint with the engine at idle (or cranking?)

Is the pressure within ± 500 psi of set point?

If psi is within 500 psi

- Document DTC and freeze frame data and attempt to duplicate complaint.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

If the psi is higher than setpoint

- Go To 7

If the psi is lower than setpoint

- Go To 5

5. LIFT PUMP FLOW

Perform the no trouble code *IN TANK FUEL LIFT PUMP FLOW TEST. In-Tank Fuel Lift Pump Flow/Diagnostic Test Procedure

Did the Lift pump pass the test?

Yes

- Go To6

No

- Replace the Lift Pump.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

6. 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 To7

7. 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 To8

No

- Replace the fuel pressure sensor.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

8. 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 To9

No

- Go To11

9. 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 To10

No

- Replace the Fuel pump.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

10. 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 To11

11. 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 To12

No

- Replace the Pressure Limiting Valve.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

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