For 1990-2009 cars

### 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 00: Fuel Pressure Regulator Performance Malfunction
DTC P0089 11: Fuel Pressure Regulator Performance Above Maximum Threshold
DTC P0089 12: Fuel Pressure Regulator Performance Below Minimum Threshold
DTC P0089 18: Fuel Pressure Regulator Performance Signal Amplitude Less Than Minimum
DTC P0089 19: Fuel Pressure Regulator Performance Signal Amplitude Greater Than Maximum

### Circuit/System Description

The engine control module (ECM) uses commanded fuel pump flow to determine a desired fuel rail pressure (FRP). The ECM monitors fuel rail pressure with the FRP sensor. The Fuel Pressure Regulator Solenoid 2 is used to control the fuel pressure at the fuel rail. The Fuel Pressure Regulator Solenoid 2 is pulse width modulated (PWM). The engine control module (ECM) supplies the voltage directly to the 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 runs continuously once the above conditions are met.

### Conditions for Setting the DTC

#### P0089 00

The ECM detects that the fuel rail pressure is above the maximum threshold while the pressure is controlled by both fuel rail pressure regulator 1 and 2.

#### P0089 11

The ECM detects that the fuel rail pressure is above the maximum threshold when the pressure is controlled by the fuel pressure regulator 1.

#### P0089 12

The ECM detects that the fuel rail pressure is below the minimum threshold when the pressure is controlled by the fuel pressure regulator 1.

#### P0089 18

Positive deviation and set point value of the fuel volume flow through the fuel pressure regulator 1 exceeded concerning set flow of fuel.

#### P0089 19

Negative rail pressure deviation and the set point value of fuel volume through the fuel pressure regulator 1 is less than or equal to the minimum value.

### Action Taken When the DTC Sets

• | DTCs P0089 00, P0089 11, and P0089 12 are Type A DTCs.

• | DTCs P0089 18, and P0089 19 are Type B DTCs.

### Conditions for Clearing the DTC

• | DTCs P0089 00, P0089 11, and P0089 12 are Type A DTCs.

• | DTCs P0089 18, and P0089 19 are Type B 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 2 will cause a DTC to set.

• | There are no driveability concerns associated with the FRP regulator unless a DTC is present. One of the causes of these DTCs is a sticking FRP 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

DW100-010-A Fuel Pressure Gage

### Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. Verify that no other DTCs are set.

⇒ | If any other DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

2. Engine running, observe the scan tool DTC information parameter. DTCs P0087, P0088, or P0089 should not set.
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 ON, command the fuel pump relay ON and OFF with a scan tool. Verify the fuel pump turns ON.

⇒ | If the fuel pump does not turn ON, refer to Fuel Pump Electrical Circuit Diagnosis for further diagnosis.

2. Ignition OFF, install the DW100-010-A Fuel Pressure Gage to the fuel supply pipe at the fuel filter assembly. Refer to Fuel Pressure Gage Installation and Removal.
3. Ignition ON, verify the fuel pressure is between 414-483 kPa (60-70 psi).

⇒ | If not within the specified range, refer to Fuel System Diagnosis for further diagnosis.

4. Ignition OFF, disconnect the harness connector at the Q18 fuel pressure regulator solenoid 1.
5. Ignition ON, verify a test lamp illuminates between the ignition 1 voltage circuit terminal 1 and ground.

⇒ | If the test lamp does not illuminate, repair the ignition 1 voltage circuit for a short to ground or an open/high resistance.

6. Ignition ON, test for 3-4 V between the control circuit terminal 2 and ground.

⇒ | 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 ECM.

⇒ | If greater than the specified range, test the control circuit for a short to voltage. If circuit tests normal, replace the K20 ECM.

7. Ignition OFF, connect the harness connector at the Q18 fuel pressure regulator solenoid 1.
8. Disconnect the harness connector of the Q18 fuel pressure regulator solenoid 2.
9. Ignition ON, verify a test lamp illuminates between the ignition 1 voltage supply circuit terminal 2 and ground.

⇒ | If the test lamp does not illuminate, test the ignition 1 voltage supply circuit for a short to ground or an open/high resistance. If circuit tests normal, replace the K20 ECM.

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

⇒ | If less than the specified range, test the control circuit for an open or a short to ground. If the circuit tests normal, replace the K20 ECM.

⇒ | If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

11. Connect the harness connector at the Q18 fuel pressure regulator solenoid 2.
12. Inspect and repair one of the following conditions:

#### Low Pressure

• | A fuel system leak

• | Restricted fuel filter

• | Injection nozzle stuck in open position

• | Leakage in the fuel rail pressure (FRP) regulator

• | Worn fuel injection pump

#### High Pressure

• | Restricted fuel return

• | Fuel injection pump stuck open

• | Fuel rail pressure (FRP) regulator stuck closed

• | Restricted fuel injector

### 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

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

### Repair Verification

Ignition ON, observe the scan tool DPF soot mass parameter. The parameter should be less than 24 grams.

⇒ | If greater than the specified range, perform a DPF service regeneration. Refer to Exhaust Particulate Filter Cleaning.