• Perform the Diagnostic System Check prior to using this diagnostic procedure:Diagnostic System Check - Vehicle
• Review the description of Strategy Based Diagnosis:Strategy Based Diagnosis
• An overview of each diagnostic category can be found here:Diagnostic Procedure Instructions

For an overview of the component/system, refer to:Fuel System Description

The control module uses the fuel pressure sensor to constantly adjust the fuel pump's feed rate so that the ideal pressure is maintained in the low pressure section (between the fuel pump and the high pressure fuel pump) by means of a closed loop control.

• DTC P018C, P018D, P0231, P0232, P023F, P0641, P1255, P0129, P12A6 = Not set
• Engine=Running—For greater than 5 s
• Fuel Pump Enable=On

Frequency the DTC runs=Continuously—After the running conditions are met

Ignition=On

Frequency the DTC runs=Continuously—After the running conditions are met

Fuel Pressure Sensor=Change is less than 30 kPa (4.4 PSI)—For greater than 5 s

Fuel Pressure Sensor=Less than 0.2 V—For greater than 1 s

Fuel Pressure Sensor=Greater than 4.8 V—For greater than 1 s

DTCs listed in the DTC Descriptor category=Type B DTC

DTCs listed in the DTC Descriptor category=Type B DTC

Engine Controls Schematics

Master Electrical Component List

Powertrain Component Views

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Control Module References

1. Ignition » On / Vehicle » In Service Mode
2. Verify DTC P0231, P0232, P023F, P0641, P1255, P0129, P12A6 is not set
• If any of the DTCs are set

  Refer to:Diagnostic Trouble Code (DTC) List - Vehicle

• If none of the DTCs are set
3. Engine»Running
4. Verify the scan tool parameter:Fuel Pressure Sensor=2.7 to 3.8 V
• If not between 2.7 and 3.8 V

  Refer to: Circuit/System Testing

• If between 2.7 and 3.8 V
5. Verify the scan tool parameter:Fuel Pressure Sensor=The value should not spike or drop out.

   Perform the action while monitoring the parameter:

• Wiggle the harness and connector(s):B47 Fuel Pressure Sensor
• Wiggle the harness and connector(s):K111 Fuel Pump Driver Control Module
• If the value spikes or drops out

  Repair as necessary » Wiring / Terminal(s) / Electrical Connector(s)

• If the value does not spike or drop out
6. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

   Verify the DTC does not set.

• If the DTC sets

  Refer to: Circuit/System Testing

• If the DTC does not set
7. All OK.

1. Ignition/Vehicle & All vehicle systems » Off
2. Disconnect the electrical connector:B47 Fuel Pressure Sensor
3. Test for less than 10 Ω between the test points:Low Reference circuit terminal 2&Ground
• If 10 Ω or greater
1. Disconnect the electrical connector:X3@K20 Engine Control Module
2. Test for less than 2 Ω between the test points:Low Reference circuit terminal 2@Component harness&Terminal 20@Control module harness
• If 2 Ω or greater » Repair the open/high resistance in the circuit.
• If less than 2 Ω » Replace the component:K20 Engine Control Module
• If less than 10 Ω
4. Ignition » On / Vehicle » In Service Mode
5. Test for 4.8 to 5.2 V between the test points:5 V Reference circuit terminal 3&Low Reference circuit terminal 2
• If less than 4.8 V
1. Ignition/Vehicle » Off
2. Disconnect the electrical connector:X2@K20 Engine Control Module
3. Test for infinite resistance between the test points:5 V Reference circuit terminal 3@Component harness&Ground
• If less than infinite resistance » Repair the short to ground on the circuit.
• If infinite resistance
4. Test for less than 2 Ω between the test points:5 V Reference circuit terminal 3@Component harness&Terminal 4@Control module harness
• If 2 Ω or greater » Repair the open/high resistance in the circuit.
• If less than 2 Ω » Replace the component:K20 Engine Control Module
• If greater than 5.2 V
1. Ignition/Vehicle » Off
2. Disconnect the electrical connector:X2@K20 Engine Control Module
3. Ignition » On / Vehicle » In Service Mode

Note: Internal control module or component damage may occur if the circuit shorts to B+.

4. Test for less than 1 V between the test points:5 V Reference circuit terminal 3@Component harness&Ground
• If 1 V or greater » Repair the short to voltage on the circuit.
• If less than 1 V » Replace the component:K20 Engine Control Module
• If between 4.8 and 5.2 V
6. Verify the scan tool parameter:Fuel Pressure Sensor=Less than 0.2 V
• If 0.2 V or greater
1. Ignition/Vehicle » Off
2. Disconnect the electrical connector:X2@K20 Engine Control Module
3. Ignition » On / Vehicle » In Service Mode
4. Test for less than 1 V between the test points:Signal circuit terminal 1@Component harness&Ground
• If 1 V or greater » Repair the short to voltage on the circuit.
• If less than 1 V » Replace the component:K20 Engine Control Module
• If less than 0.2 V
7. Connect a 3 A fused jumper wire between the test points:Signal circuit terminal 1&5 V Reference circuit terminal 3
8. Verify the scan tool parameter:Fuel Pressure Sensor=Greater than 4.8 V
• If 4.8 V or less
1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
2. Disconnect the electrical connector:X2@K20 Engine Control Module
3. Test for infinite resistance between the test points:Signal circuit terminal 1@Component harness&Ground
• If less than infinite resistance » Repair the short to ground on the circuit.
• If infinite resistance
4. Test for less than 2 Ω between the test points:Signal circuit terminal 1@Component harness&Terminal 20@Control module harness
• If 2 Ω or greater » Repair the open/high resistance in the circuit.
• If less than 2 Ω » Replace the component:K20 Engine Control Module
• If greater than 4.8 V
9. Test or replace the component:B47 Fuel Pressure Sensor

Perform the Diagnostic Repair Verification after completing the repair:Diagnostic Repair Verification

• Fuel Pressure Sensor Replacement - Fuel Feed Pipe
• For control module replacement, programming, and setup refer to:Control Module References