Vauxhall Workshop Service and Repair Manuals

DTC P0251-P0254

Diagnostic Instructions

DTC Descriptors

Diagnostic Fault Information

Circuit/System Description

The fuel pressure regulator is used to control the fuel pressure at the high pressure pump. The fuel pressure regulator is pulse width modulated (PWM). The engine control module (ECM) supplies the voltage directly to the fuel pressure regulator. The ECM controls the solenoid by grounding the control circuit with a solid state device called a driver.

Conditions for Running the DTC

Conditions for Setting the DTC

P0251

The ECM detects the Fuel Pressure Regulator Control Circuit is open for more than 1 s.

P0252 54

The ECM detects an overtemperature at the output control driver of the fuel pressure regulator.

P0253

The ECM detects the fuel pressure regulator control circuit is shorted to ground for more than 1 second.

P0254

The ECM detects the fuel pressure regulator control circuit is shorted to voltage for more than 1 s.

Action Taken When the DTC Sets

DTC P0251, P0252 54, P0253 and P0254 are type A DTCs.

Conditions for Clearing the DTC

DTC P0251, P0252 54, P0253 and P0254 are type A DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. DTCs P0251, P0252 54, P0253 or P0254 should not set.
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 listed below.

•	LBS Q18 Fuel Pressure Regulator

•	LBY Q18A Fuel Pressure Regulator 1

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

•	LBS Terminal 1

•	LBY Terminal 2

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

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

•	LBS Terminal 2

•	LBY Terminal 1

⇒	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 Engine Control Module.

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

4. Test for less than 5 Ω on the ignition voltage circuit and the control circuit.

⇒	If greater than the specified range, repair the appropriate circuit for a high resistance.

5. If all circuits test normal, test or replace the component listed below.

•	LBS Q18 Fuel Pressure Regulator

•	LBY Q18A Fuel Pressure Regulator 1

Component Testing

Static Test

1. Ignition OFF, disconnect the harness connector at the component listed below.

•	LBS Q18 Fuel Pressure Regulator

•	LBY Q18A Fuel Pressure Regulator 1

2. Test for 2.5-3.5 Ω between the control terminal 2 and the ignition voltage terminal 1.

⇒	If not within the specified range, replace the Fuel Pressure Regulator.

3. Test for infinite resistance between each terminal and the solenoid Fuel Pressure Regulator housing.

⇒	If not the specified value, replace the Fuel Pressure Regulator.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.