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DTC P0089

DTC P0089

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 P0089 51

Fuel Pressure Regulator Performance

DTC P0089 52

Fuel Pressure Regulator Performance

DTC P0089 54

Fuel Pressure Regulator Performance

DTC P0089 57

Fuel Pressure Regulator Performance

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 and Fuel Pressure Regulator Solenoid 2 are used to control the fuel pressure at the fuel rail. The Fuel Pressure Regulator Solenoid 1 and Fuel Pressure Regulator Solenoid 2 are pulse width modulated (PWM). The ECM supplies the voltage directly to the Fuel Pressure Regulator Solenoid 1 and Fuel Pressure Regulator Solenoid 2. 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

P0089 51

The ECM detects that the fuel rail pressure is above the maximum threshold.

P0089 52

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

P0089 54

The ECM detects an overtemperature at the power stage of the fuel pressure regulator 2.

P0089 57

The engine start delayed due to faulty fuel pressure regulator 2

Action Taken When the DTC Sets

DTCs P0089 are Type C DTCs.

Conditions for Clearing the DTC

DTCs P0089 are Type C 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 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 scan tool parameter DTC information. DTC P0087, P0088 or P0089 are not 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 a test lamp illuminates between the ignition voltage circuit terminal 2 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 1 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. Ignition OFF, disconnect the harness connector at the Q45B Fuel Rail Pressure Regulator 2.

13. Ignition ON, verify a test lamp illuminates between the ignition voltage circuit terminal 2 and ground.

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

15. Ignition ON, test for 3-4 V between the control circuit terminal 1 and ground.

16. 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.

17. 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.

18. 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

19. If all circuit tests normal, replace the Q45A Fuel Rail Pressure Regulator 1 or Q45B Fuel Rail Pressure Regulator 2.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


• Fuel Injection Fuel Rail Assembly Replacement

• Fuel Injection Pump Replacement

• Fuel Injector Replacement (LBY/A20DTR) Fuel Injector Replacement (LBS/A20DTH)

• Control Module References for ECM replacement, setup, and programming