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DTC P0087 or P0088 (LCD, LBX, LBS)

DTC P0087 or P0088 (LCD, LBX, LBS)

Diagnostic Instructions


Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.


DTC Descriptors

DTC P0087 51

Fuel Rail Low Pressure Malfunction

DTC P0087 53

Fuel Rail Low Pressure Malfunction

DTC P0087 55

Fuel Rail Low Pressure Too Few Transitions

DTC P0088 51

Fuel Rail High Pressure Malfunction

DTC P0088 52

Fuel Rail High Pressure Malfunction

DTC P0088 53

Fuel Rail High Pressure Malfunction

DTC P0088 54

Fuel Rail High Pressure Malfunction

DTC P0088 57

Fuel Rail High Pressure Malfunction

DTC P0088 58

Fuel Rail High Pressure Performance

DTC P0088 59

Fuel Rail High Pressure Protection Time-Out

DTC P0088 5A

Fuel Rail High Pressure Not Plausible

DTC P0088 5D

Fuel Rail High Pressure Malfunction

Circuit/System Description

The engine control module (ECM) uses commanded fuel pump flow to determine a desired fuel rail pressure. The ECM monitors fuel rail pressure with the fuel rail pressure sensor. The Fuel Pressure Regulator Solenoid 1 is used to control the fuel pressure at the fuel rail. The Fuel Pressure Regulator Solenoid 1 is pulse width modulated (PWM). The ECM supplies the voltage directly to the Fuel Pressure Regulator Solenoid 1. The ECM controls the solenoid by grounding the control circuit with a solid state device called a driver.

Conditions for Running the DTC


The engine is running.

The DTCs run continuously when the above conditions are met.


Conditions for Setting the DTC

P0087 51, P0087 53 and P0087 55

The ECM detects that the rail pressure is below the minimum threshold.

P0088 51, P0088 52, P0088 58, P0088 59, P0088 5A and P0088 5D

The ECM detects that the rail pressure exceeds the maximum positive deviation of rail pressure.

P0088 53

The ECM detects that the rail pressure exceeds the minimum rail pressure.

P0088 54, P0088 57

The ECM detects that the rail pressure exceeds the maximum rail pressure.

Action Taken When the DTC Sets

DTCs P0087 51, P0087 53, P0087 55, P0088 51, P0088 52, P0088 58, P0088 59, P0088 5A, P0088 5D, P0088 53, P0088 54, and P0088 57 are Type A DTCs.

Conditions for Clearing the DTC

DTCs P0087 51, P0087 53, P0087 55, P0088 51, P0088 52, P0088 58, P0088 59, P0088 5A, P0088 5D, P0088 53, P0088 54, and P0088 57 are Type A DTCs.

Diagnostic Aids


A restricted fuel supply line, a leakage in the high pressure section, too much or too little fuel in the low pressure line may cause DTCs to set. When ambient temperatures are below 0°C (32°F), the fuel tank pickup screen may be iced over from water in the fuel tank.

High Resistance in either circuit of the Fuel Pressure Regulator 1 will cause a DTC to set.

There are no driveability concerns associated with the fuel rail pressure regulator unless a DTC is present. One of the causes of these DTCs is a sticking fuel rail pressure regulator.

If the fuel system pressure is actually too high, a fuel knock and smoke condition will exist.


Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Fuel System Description

Electrical Information Reference


Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs


DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EN 34730-1A Fuel Pressure Gauge

For equivalent regional tools, refer to Special Tools .

Circuit/System Verification


1. Ignition ON, observe the DTC information with a scan tool. Verify that no other DTCs are set.

2. If any other DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

3. Engine ON, observe the DTC's information parameter on the scan tool. DTCs P0087 or P0088 should not be set.

4. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.


Circuit/System Testing


1. Ignition ON, command the fuel pump ON and OFF with a scan tool. Verify the fuel pump turns ON.

2. If the fuel pump does not turn ON, refer to Fuel Pump Electrical Circuit Diagnosis for further diagnosis.

3. Ignition OFF, install the fuel pressure gauge EN-34730-1A

4. Ignition ON, verify the fuel pressure is between 414-550 kPa (60-80 PSI).

5. If not within the specified range, refer to Fuel System Diagnosis for further diagnosis.

6. Ignition OFF, disconnect the harness connector at the Q45A Fuel Rail Pressure Regulator 1.

7. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal 1 and ground.

8. If the test lamp does not illuminate, repair the ignition voltage circuit for a short to ground or an open/high resistance.

9. Ignition ON, test for 3-4 V between the control circuit terminal 2 and ground.

10. If less than the specified range, test the control circuit for an open or a short to ground. If circuit tests normal, replace the K20 Engine Control Module.

11. If greater than the specified range, test the control circuit for a short to voltage. If circuit tests normal, replace the K20 Engine Control Module.

12. Inspect and repair one of the following conditions:

A fuel system leak

Restricted fuel filter

Injection nozzle stuck in open position

Leakage in the fuel rail pressure regulator

Worn fuel injection pump

Restricted fuel return

Fuel injection pump stuck open

Fuel rail pressure regulator stuck closed

Restricted fuel injector

13. If all circuit tests normal, replace the Q45A Fuel Rail Pressure Regulator 1.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


Fuel Injection Pump Replacement

Fuel Injector Replacement

Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement

Control Module References for ECM replacement, setup, and programming