P0088-FUEL RAIL PRESSURE TOO HIGH
For a complete wiring diagram, refer to the Wiring Information.
High Pressure fuel lines deliver
diesel fuel under extreme pressure from the injection pump to the
fuel injectors. This may be as high as 23,200 PSI (1600BAR). Use extreme
caution when inspecting for high pressure fuel leaks. Failure to follow
these instructions may result in possible serious or fatal injury.
WARNING:
Fuel under this amount of pressure
can penetrate skin causing possible serious or fatal injury. Inspect
for high pressure fuel leaks with a sheet of cardboard. Wear safety
goggles and adequate protective clothing when servicing fuel system.
Failure to follow these instructions may result in possible serious
or fatal injury.
WARNING:
-
When Monitored:
With the engine running.
-
Set Condition:
The Powertrain Control Module (PCM) determines that the fuel rail pressure is too high for a given engine speed and load.
Possible Causes |
|---|
| AIR IN FUEL SYSTEM |
| FUEL DELIVERY SYSTEM |
| FUEL PRESSURE SENSOR |
| FUEL INJECTOR(S) |
| FUEL PRESSURE REGULATOR |
| HIGH PRESSURE DELIVERY PUMP |
| FUEL SYSTEM CONTAMINATION |
| FUEL SYSTEM LEAK |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
1. CHECKING FOR OTHER PCM DTCS
| 1. | Turn the ignition on. |
| 2. | With the scan tool, read the PCM DTCs. |
Are there any other DTCs present?
Yes
- Repair the other DTCs before continuing.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Go To 2
| 1. | Turn the ignition on. |
| 2. | With the scan tool, erase the PCM DTCs. |
| 3. | Test drive the vehicle under various load and speed conditions to attempt to duplicate the fault. |
| 4. | With the scan tool, read the PCM DTCs. |
Did the DTC return?
Yes
- Go To 3
No
- Perform the INTERMITTENT DTC diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
| 1. | Turn the ignition off. |
| 2. | Inspect the entire fuel system for leakage. |
Is there any evidence of leakage?
Yes
- Repair as necessary in accordance with the service information.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Go To 4
| 1. | Inspect the fuel system for contamination. |
Is the fuel contaminated?
Yes
- Repair as necessary in accordance with the service information.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Go To 5
| 1. | With the scan tool, erase the PCM DTCs. |
| 2. | Attempt to start the engine. |
Does the engine start and idle?
Yes
- Go To 6
No
- Go To 11
6. CHECKING FOR AIR IN FUEL SYSTEM
| 1. | With the scan tool in Sensors, compare the Fuel Pressure Setpoint with the Actual Fuel Pressure readings. |
| NOTE: | If there is air in the fuel system, the Actual Fuel Pressure will oscillate more than 100 PSI above and/or below the Fuel Pressure Setpoint. |
Does Actual Fuel Pressure oscillate more than 100 psi above and/or below the Fuel Pressure Setpoint?
Yes
- Refer to the service information to purge air from the fuel system.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Go To 7
| 1. | With the scan tool, compare the Fuel Pressure Setpoint with the Actual Fuel Pressure. |
| NOTE: | A sticking Fuel Pressure Regulator is indicated by the Actual Fuel Pressure gradually dropping below the Fuel Pressure Setpoint then suddenly increasing (spiking) above the Fuel Pressure Setpoint. |
Does the Actual Fuel Pressure gradually decrease then suddenly increase (spike) above the Fuel Pressure Setpoint?
Yes
- Replace the Fuel Rail Assembly in accordance with the service information.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Go To 8
8. CHECKING FUEL DELIVERY SYSTEM
| 1. | Perform the CHECKING THE FUEL DELIVERY SYSTEM diagnostic procedure. (Refer to 29 - Non-DTC Diagnostics/Drivability - Diesel - Diagnosis and Testing) . |
Were there any problems with the Fuel Delivery System?
Yes
- Repair as necessary in accordance with the service information.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Go To 9
| NOTE: | An injector that sticks open can cause this DTC. A sticking injector will cause the engine to misfire and emit excessive black smoke from the exhaust system. |
Does the engine exhibit the symptoms described in the above note?
Yes
- Using the service information, remove and inspect the Fuel Injectors for signs of damage or debris that may cause the injector to stick. Sticking injectors may cause the combustion chamber to become black and oil soaked. Replace Injector(s) as necessary.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Go To 10
| 1. | Turn the ignition off. |
| 2. | Replace the Fuel Pressure Regulator in accordance with the service information. |
| 3. | Turn the ignition on. |
| 4. | With the scan tool, erase the PCM DTCs. |
| 5. | Attempt to start and test drive the vehicle. |
| 6. | With the scan tool, read the PCM DTCs. |
Did the DTC return?
Yes
- Replace the High Pressure Delivery Pump in accordance with the service information.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
11. CHECKING FUEL DELIVERY SYSTEM
| 1. | Perform the CHECKING THE FUEL DELIVERY SYSTEM diagnostic procedure. (Refer to 29 - Non-DTC Diagnostics/Drivability - Diesel - Diagnosis and Testing) . |
Were there any problems with the Fuel Delivery System?
Yes
- Repair as necessary in accordance with the service information.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Go To 12
| 1. | Turn the ignition off. |
| 2. | Replace the Fuel Pressure Regulator in accordance with the service information. |
| 3. | Turn the ignition on. |
| 4. | With the scan tool, erase the PCM DTCs. |
| 5. | Attempt to start and test drive the vehicle. |
| 6. | With the scan tool, read the PCM DTCs. |
Did the DTC return?
Yes
- Go To 13
No
- Test Complete.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
| 1. | Turn the ignition off. |
| 2. | Replace the Fuel Quantity Solenoid in accordance with the service information. |
| 3. | Turn the ignition on. |
| 4. | With the scan tool, erase the PCM DTCs. |
| 5. | Attempt to start and test drive the vehicle. |
| 6. | With the scan tool, read the PCM DTCs. |
Did the DTC return?
Yes
- Replace the High Pressure Delivery Pump in accordance with the service information.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Test Complete.
- Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).