P0088-FUEL RAIL PRESSURE TOO HIGH
For the Engine circuit diagram (Refer to 9 - ENGINE - SCHEMATICS AND DIAGRAMS).
For a complete wiring diagram Refer to Section 8W
- When Monitored:
With the engine running.
- Set Condition:
The ECM 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 INJECTOR(S) |
| FUEL PRESSURE SOLENOID |
| FUEL PUMP |
| FUEL SYSTEM CONTAMINATION |
| FUEL SYSTEM LEAK |
| INTERMITTENT DTC |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Diagnostic Test
1.CHECKING FOR OTHER ECM DTCSWARNING: 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 (1600 BAR). USE EXTREME CAUTION WHEN INSPECTING FOR HIGH-PRESSURE FUEL LEAKS.
WARNING: FUEL UNDER THIS AMOUNT OF PRESSURE CAN PENETRATE SKIN CAUSING PERSONAL INJURY OR DEATH. INSPECT FOR HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF CARDBOARD. WEAR SAFETY GOGGLES AND ADEQUATE PROTECTIVE CLOTHING WHEN SERVICING FUEL SYSTEM.
Are there any other DTCs present?
Yes
- Refer to symptom list for problems related to the DTC other than this DTC.
- Perform the ECM VERIFICATION TEST.
No
- Go To 2
2.CURRENT DTC
NOTE: Refer to the Service Information and perform the Air Bleed Procedure before continuing diagnosis.
NOTE: Driving the vehicle up and down steep hills or rapid cornering with a low fuel level can cause this DTC to set. Verify with customer if Low Fuel Light was illuminated when fault occurred.
Does the scan tool display this DTC?
Yes
- Go To 3
No
- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
3.FUEL SYSTEM LEAK
WARNING: 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 (1600 BAR). USE EXTREME CAUTION WHEN INSPECTING FOR HIGH-PRESSURE FUEL LEAKS.
WARNING: FUEL UNDER THIS AMOUNT OF PRESSURE CAN PENETRATE SKIN CAUSING PERSONAL INJURY OR DEATH. INSPECT FOR HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF CARDBOARD. WEAR SAFETY GOGGLES AND ADEQUATE PROTECTIVE CLOTHING WHEN SERVICING FUEL SYSTEM.
NOTE: This vehicle is not equipped with an in-tank fuel lift pump. The high pressure fuel pump draws (vacuums) the fuel from the fuel tank. Even a very small leak in the fuel supply system between the fuel tank and high-pressure pump can cause driveability problems and dtc's to set.
Is there any evidence of leakage?
Yes
- Repair as necessary in accordance with the Service Information.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
- Go To 4
4.FUEL SYSTEM CONTAMINATION
NOTE: Mixing any other fuels such as gasoline or kerosine can cause this DTC to set.
WARNING: 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 (1600 BAR). USE EXTREME CAUTION WHEN INSPECTING FOR HIGH-PRESSURE FUEL LEAKS.
WARNING: FUEL UNDER THIS AMOUNT OF PRESSURE CAN PENETRATE SKIN CAUSING PERSONAL INJURY OR DEATH. INSPECT FOR HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF CARDBOARD. WEAR SAFETY GOGGLES AND ADEQUATE PROTECTIVE CLOTHING WHEN SERVICING FUEL SYSTEM.
Is the fuel contaminated?
Yes
- Repair as necessary in accordance with the Service Information.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
- Go To 5
5.FUEL PRESSURE SENSOR CALIBRATION
Does the scan tool display between 0.45 and 0.55 volts for the Fuel Pressure Sensor?
Yes
- Go To 6
No
- Check the Fuel Pressure Sensor wiring and connectors for corrosion or poor terminal contact that could cause high resistance. repair as necessary. If wiring and connectors are o.k., replace the Fuel Pressure Sensor.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
6.ATTEMPT TO START ENGINE
Does the engine start and idle?
Yes
- Go To 7
No
- Go To 12
7.CHECKING FOR AIR IN FUEL SYSTEM
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 ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
- Go To 8
8.FUEL PRESSURE SOLENOID
NOTE: A sticking Fuel Pressure Solenoid 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 Pressure Solenoid in accordance with the Service Information.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
- Go To 9
9.CHECKING FUEL DELIVERY SYSTEM
NOTE: The following is a list of problems that can cause fuel pressure to deviate from specification: restricted fuel filter or fuel lines, failed fuel pressure solenoid, air in fuel system, failed fuel sending unit, contaminated fuel, faulty injector.
NOTE: This vehicle is not equipped with an in-tank fuel lift pump. The high pressure fuel pump draws (vacuums) the fuel from the fuel tank. Even a very small leak in the fuel supply system between the fuel tank and high-pressure pump can cause driveability problems and dtc's to set.
Were there any problems with the Fuel Delivery System?
Yes
- Repair as necessary in accordance with the Service Information.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
- Go To 10
10.FUEL INJECTOR(S)
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 ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
- Go To 11
11.FUEL PRESSURE SOLENOID
Does the ECM display this DTC?
Yes
- Replace the Fuel Pump in accordance with the Service Information.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
- Test Complete.
12.CHECKING FUEL DELIVERY SYSTEM
NOTE: The following is a list of problems that can cause fuel pressure to deviate from specification: restricted fuel filter or fuel lines, failed fuel pressure solenoid, air in fuel system, failed fuel sending unit, contaminated fuel, faulty injector.
Were there any problems with the Fuel Delivery System?
Yes
- Repair as necessary in accordance with the Service Information.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
- Go To 13
13.FUEL PRESSURE SOLENOID
Does the ECM display this DTC?
Yes
- Go To 14
No
- Test Complete.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
14.FUEL QUANTITY SOLENOID
Did this DTC set again?
Yes
- Replace the Fuel Pump in accordance with the Service Information.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
- Test Complete.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)