P0087

DTC P0087, P0088, or P0089

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptors
DTC P0087
- Fuel Rail Low Pressure

DTC P0088
- Fuel Rail High Pressure

DTC P0089
- Fuel Pressure Regulator Performance

Circuit/System Description

The fuel rail pressure sensor detects fuel pressure within the fuel rail. The engine control module (ECM) provides a 5 V reference voltage on the 5 V reference circuit and ground on the low reference circuit. The ECM receives a varying signal voltage on the signal circuit.

High pressure fuel is regulated by the high pressure fuel pump actuator, which is a part of the high pressure fuel pump. The high pressure fuel pump actuator is a solenoid valve. The ECM provides a voltage on the actuator high control circuit and ground on the actuator low control circuit. Both circuits are controlled through output drivers within the ECM. When deactivated, both drivers are disabled. When activated, the high control circuit driver energizes the high pressure fuel pump actuator and the low control circuit driver pulse-width modulates (PWM) the low control circuit to ground.

The high pressure mechanical fuel pump is driven by three lobes on the camshaft. The ECM uses the camshaft and crankshaft position sensor inputs to synchronize the high pressure fuel pump actuator with the position of each of the camshaft lobes. The ECM regulates fuel pressure by adjusting the portion of each pump stroke that provides fuel to the rail.

The ECM monitors the fuel rail pressure sensor and the high pressure fuel pump actuator to determine if the commanded and actual pressure are within a predetermined range, or if the amount of fuel pressure correction exceeds a calibrated pressure.

Conditions for Running the DTC

* DTC P0090, P0091, P0092, P0191, P0192, or P0193 is not set.
* The ignition voltage is less than 18 V.
* The deceleration fuel cut-off (DFCO) is inactive.
* The engine speed is greater than 25 RPM.
* The air bag is not deployed.
* DTCs P0087, P0088, and P0089 run continuously when the above conditions are met for 5 seconds.

Conditions for Setting the DTC

P0087

The actual fuel rail pressure is 1.5 MPa (218 psi) less than the desired fuel pressure. The condition exists for greater than 5 seconds.

P0088

The actual fuel rail pressure is 3.6 MPa (522 psi) greater than the desired fuel rail pressure. The condition exists for greater than 5 seconds.

P0089

The high pressure fuel pump actuator command necessary to maintain the desired fuel rail pressure is +/-2.5 MPa (363 psi) of the command expected by the controller. The condition exists for greater than 5 seconds.

Action Taken When the DTC Sets

* DTCs P0087, P0088, and P0089 are Type A DTCs.
* A message center or an indicator displays Reduced Engine Power.

Conditions for Clearing the DTC

DTCs P0087, P0088, and P0089 are Type A DTCs.

Diagnostic Aids

* A restricted fuel feed pipe between the fuel feed pipe fuel pressure sensor and the high pressure fuel pump may set a DTC.
* A condition with the fuel tank fuel pump module or the fuel pump flow control module may set a DTC.
* A skewed fuel rail pressure sensor or an intermittent condition in the fuel rail pressure sensor circuits may set a DTC.
* A leaking or restricted fuel injector may set a DTC.

Reference Information
Schematic Reference

Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Fuel System Description (Fuel System Description)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing For Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

1. Observe the DTC information with a scan tool. DTC P029D, P02A1, P02A5, P02A9, P02AD, P02B1, P0627, P0628, P0629, P069E, or U0109 should not set.

• If a DTC is set refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle).

2. Attempt to start and idle the engine.
3. Observe the DTC information with a scan tool. DTCs P0087, P0088, and P0089 should not set.
4. Engine idling, observe the Fuel Rail Pressure Sensor parameter with a scan tool. The pressure should be approximately 3.5-5.5 Mpa (508-798 psi).
5. Command an increase and decrease in fuel rail pressure with a scan tool. Observe the scan tool Fuel Rail Pressure Sensor parameter. The Fuel Rail Pressure Sensor should increase or decrease with each commanded state.
6. 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

Note: Circuit/System Verification must be performed first or misdiagnosis may result.

1. Ignition ON, observe the scan tool fuel pump control module (FPCM) fuel line pressure sensor parameter. Command an increase in the fuel line pressure with a scan tool. Verify the fuel line pressure increases to greater than 410 kPa (60 psi) as commanded.

• If the less than the specified range, refer to Fuel System Diagnosis (Fuel System Diagnosis).

Note: As little as 2 ohm on either circuit of the high pressure fuel pump actuator will cause these DTCs to set. Test the circuits of the high pressure fuel pump actuator for a high resistance if you suspect a condition.

2. Remove the Q18 high pressure fuel pump assembly and visually inspect the lobes on the camshaft for unusual wear.

• If the lobes appear normal, replace the Q18 high pressure fuel pump assembly.
• If the lobes are worn, replace the camshaft.

Component Testing
Static Test

1. Ignition OFF, disconnect the harness connector at the high pressure fuel pump.

Note: The DMM and test leads must be calibrated to 0 ohm in order to prevent misdiagnosis.

2. Test for 0.35-0.6 ohm at 20°C (68°F) between low control circuit terminal 1 and high control circuit terminal 2.

• If the resistance is less than 0.3 ohm or greater than 0.6 ohm, replace the high pressure fuel pump.

3. Test for infinite resistance between each terminal and the high pressure fuel pump housing/case.

• If not the specified value, replace the high pressure fuel pump.

Dynamic Test

Engine idling, command the Fuel Pressure Control to Increase with a scan tool. The Fuel Rail Pressure Sensor parameter should increase with each command.

If the Fuel Rail Pressure Sensor parameter does not increase with each command, replace the G18 high pressure fuel pump.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Camshaft Removal - Left Side (LLT) (35. Camshaft Removal - Left Side)
* Fuel Pump Replacement (Fuel Pump Replacement)