P0092

DTC P0091 or P0092

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 Descriptor
DTC P0091
- Fuel Pressure Regulator Solenoid 1 Control Circuit Low Voltage

DTC P0092
- Fuel Pressure Regulator Solenoid 1 Control Circuit High Voltage

Diagnostic Fault Information





Typical Scan Tool Data













Circuit/System Description

The engine control module (ECM) controls the fuel rail pressure by controlling fuel pressure regulator 1 and fuel pressure regulator 2 simultaneously to achieve the desired fuel rail pressure. Fuel pressure regulator 1 is located on the fuel injection pump and controls the amount of fuel allowed into the high pressure side of the injection pump. If the ECM detects a fault on either of the fuel pressure regulator 1 circuits a DTC will be set.

Conditions for Running the DTC

* Engine speed is greater than 600 RPM.
* Battery voltage is greater than 11 V.

Conditions for Setting the DTC

DTC P0091
* The ECM detects low voltage on the control circuit of fuel pressure regulator 1
* The above condition exists for greater than 1 s.

DTC P0092
* The ECM detects high voltage on the control circuit of fuel pressure regulator 1.
* The above condition exists for greater than 1 s.

Action Taken When the DTC Sets

* DTC's P0091 and P0092 are Type A DTCs.
* The ECM commands the engine to operate in the Reduced Engine Power mode.
* The message center displays Reduced Engine Power.

Conditions for Clearing the DTC

DTC's P0091 and P0092 are Type A DTCs.

Diagnostic Aids

* A no start condition may exist if the fuel pressure regulator 1 control circuit is short to ground.
* No driveablity concerns may be present if the fuel pressure regulator 1 control circuit is shorted to voltage.
* If the fuel system pressure is actually too high, a fuel knock condition will exist.

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. Engine Running, observe the following scan tool parameters:

* Fuel Press. Reg. 1 Ctrl. Ckt. Short to Gnd Test Status
* Fuel Press. Reg. 1 Ctrl. Ckt. Open Test Status
* Fuel Press. Reg. 1 High Ctrl. Ckt. Short Volts Test Status
Each parameter should display OK or Not Run.

2. 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 OFF, disconnect the harness connector at the Q45A Fuel Pressure Regulator 1.
2. Ignition ON, verify that a test lamp does not illuminate between the Fuel Rail Pressure Regulator Low Reference circuit terminal 2 and ground.

• If the test lamp illuminates, test the Fuel Rail Pressure Regulator Low Reference circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.

3. Ignition OFF, ECM powered down. Connect a test lamp between the Fuel Rail Pressure Regulator Low Reference circuit terminal 2 and B+.
4. Ignition ON, verify the test lamp illuminates between the Fuel Rail Pressure Regulator Low Reference circuit terminal 2 and B+.

• If the test lamp does not illuminate, test the Fuel Rail Pressure Regulator Low Reference circuit terminal 2 for an open or high resistance. If the circuit tests normal, replace the K20 engine control module.

5. Ignition OFF, Observe that the test lamp flashes 2 times and remains OFF until the ECM is powered down.

• If the test lamp does not flash 2 times and turn OFF, test the Fuel Rail Pressure Regulator Low Reference circuit terminal 2 for a short to ground. If the circuit tests normal, replace the K20 engine control module.

6. If the circuits tests normal, replace the Q45A fuel pressure regulator 1.

Repair Instructions

Note: During code clearing, the ECM must be powered down. Power down is achieved by turning off the ignition key and waiting for loss of communication, indicating power down. The time to power down may vary from vehicle to vehicle. After power down is achieved, turn the ignition key to the ON position and clear the trouble code using the scan tool clear code function and power down ECM. Repeat power down if the trouble code does not clear on first attempt.

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

* Fuel Pressure Regulator Replacement (Service and Repair)
* Perform the scan tool Diesel Particulate Filter (DPF) Regeneration Enable (Diesel Particulate Filter (DPF) Regeneration Enable) procedure if the scan tool DPF Soot Mass is less than 30 g. If the scan tool DPF Soot Mass is 30 g or greater, perform the Diesel Particulate Filter (DPF) Service Regeneration (Diesel Particulate Filter (DPF) Service Regeneration) procedure.
* Control Module References (Programming and Relearning) for ECM replacement, programming, and setup.