GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2009 🢒 Regal 🢒 DTC 🢒 DTC P0090, P0091, or P0092

DTC P0090, P0091, or P0092 LDK with Turbocharger

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 P0090: Fuel Pressure Regulator Control Circuit

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

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

FRP regulator High

P0091

P0090

--

FRP regulator Low

--

P0090

P0092

Circuit/System Description

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

Conditions for Running the DTC
    • The ignition 1 signal parameter is between 10-18.1V.
    • The engine speed is greater than 80 RPM.
    • The DTCs run continuously within the enabling condition.

Conditions for Setting the DTC

P0090

    • The fuel pressure regulator voltage is between 1-4.5V with the fuel pressure regulator commanded OFF.
    • The DTC sets when the above condition is present for 1 second.

P0091

    • The fuel pressure regulator voltage is less than 2.7V with the fuel pressure regulator commanded OFF.
    • The DTC sets when the above condition is present for 1 second.

P0092

    • The fuel pressure regulator voltage is greater than 4.5V with the fuel pressure regulator commanded ON.
    • The DTC sets when the above condition is present for 1 second.

Action Taken When the DTC Sets
    • DTCs P0090, P0091, and P0092 are Type B DTCs.
    • A message center or an indicator displays Reduced Engine Power.

Conditions for Clearing the DTC

DTCs P0090, P0091, and P0092 are Type B DTCs.

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

Circuit/System Verification
  1. Engine idling, observe the Actual Fuel Rail Pressure parameter with a scan tool. The pressure should be approximately 3.5-5.5 Mpa (508-798 psi).
  2. Command an increase and decrease in fuel pressure with a scan tool. Observe the scan tool Desired Fuel Rail Pressure and the Actual Fuel Rail Pressure parameters. The Desired Fuel Rail Pressure and the Actual Fuel Rail Pressure should closely match in all the commanded states.
  3. 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 G18 high pressure fuel pump.
  2. Engine running, verify that a test lamp flashes between the FRP regulator low circuit terminal 1 and B+.
    3. ⇒If the test lamp is always ON, test the FRP regulator low circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
    ⇒If the test lamp is always OFF, test the FRP regulator low circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
  3. Ignition ON, verify that a test lamp illuminates between the FRP regulator high circuit terminal 2 and ground.
    4. ⇒If the test lamp does not illuminate, test the FRP regulator high circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
  4. If all circuits test normal, test or replace the G18 high pressure fuel pump.

Component Testing

Static Test

  1. Ignition OFF, disconnect the harness connector at the G18 high pressure fuel pump.
  2. Test for 0.49 ohm plus/minus 0.023 ohm at 20°C (68°F) of resistance between FRP regulator low circuit terminal 1 and FRP regulator high circuit terminal 2.
    3. ⇒If not within the specified range, replace the G18 high pressure fuel pump.
  3. Test for infinite resistance between each terminal and the high pressure fuel pump housing/case.
    4. ⇒If not the specified value, replace the G18 high pressure fuel pump.

Dynamic Test

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

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming