P0090

DTC P0090

Diagnostic Instructions

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

DTC Descriptor

DTC P0090
- Fuel Pressure Regulator Control Circuit

Diagnostic Fault Information






Circuit/System Description

High pressure fuel is regulated by the fuel rail pressure (FRP) regulator mounted on the fuel injection pump. The FRP regulator is controlled by the engine control module (ECM). The FRP regulator has a solenoid supply voltage circuit and solenoid control circuit. The ECM monitors the current on the circuits to detect a failure.

Conditions for Running the DTC

* The ignition is ON.
* The commanded FRP regulator current is between 64-1,500 mA.

Conditions for Setting the DTC

The FRP regulator circuit current is not between 50-1,600 mA.

Action Taken When the DTC Sets

DTC P0090 is a Type A DTC.

Conditions for Clearing the DTC

DTC P0090 is a Type A DTC.

Diagnostic Aids

* There are no driveability concerns associated with the FRP regulator unless a DTC is present. The most likely cause of this DTC is a sticking FRP regulator.
* If the fuel system pressure is actually too high, a fuel knock and smoke condition will exist.
* If the fuse that supplies voltage to terminal C1-76 of the ECM is open, this DTC will set.

Circuit/System Verification

Important: If you cannot duplicate the condition, operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

* Turn ON the ignition and observe that the Desired FRP Regulator parameter and the FRP Regulator Command are at the same mA values. The FRP Regulator Command should be at 16 percent.
* The fuel pressure difference between the Actual Fuel Rail Pressure and the Desired Fuel Rail Pressure should be less than 5 MPa.
* Inspect the fuel supply lines to ensure that there is no damage between the fuel tank and the fuel injection pump.
* Engine running, observe the DTC information with a scan tool. DTC P0090 should not set.
* Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame Records data.

Circuit/System Testing

Important: Failure to allow the ECM communications to completely terminate with the scan tool may result in misdiagnosis.

If DTC U0105, P0087, or P0088 are also set, Refer to Diagnostic Trouble Code (DTC) List - Vehicle. Diagnostic Trouble Code Descriptions

1. Turn OFF the ignition for 30 seconds or until the ECM is powered down.
2. Disconnect the FRP regulator in-line connector.
3. Probe the solenoid control circuit terminal 2 with a test lamp connected to ground. The test lamp should not illuminate.

Important: A solenoid control circuit that is shorted to voltage will illuminate the test lamp on both the supply voltage circuit and the solenoid control circuit.

• If the test lamp illuminates, test the solenoid control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. Turn On the ignition.
5. Connect the test lamp between the solenoid supply voltage circuit, terminal 1 and a ground. The test lamp should illuminate.

• If the test lamp did not illuminate, test the solenoid supply voltage circuit for an open. If the circuit tests normal, replace the ECM.

6. Connect the test lamp between the solenoid supply voltage circuit, terminal 1 and the solenoid control circuit, terminal 2. The test lamp should illuminate.

• If the test lamp did not illuminate, test the solenoid control circuit for an open. If the circuit tests normal, replace the ECM.

7. Test the harness between the inline connector and the FRP regulator for an open or short to voltage. If the circuits tests normal, replace the FRP regulator.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

* Control Module References Programming and Relearning
* Fuel Pressure Regulator Replacement Verification Tests