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DTC P0191

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 Descriptor

DTC P0191: Fuel Rail Pressure Sensor Performance

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

5 V Reference Voltage

P0192, P0193, P0340, P0345, P0365, P0390, P0506, P0641, P2227

P0192

P0193, P0641, P2227, P2229

P0191

Fuel Rail Pressure Sensor Signal

P0192

P0192, P0193

P0193

P0191

Low Reference

-

P0193

P0193

P0191

Circuit/System Description

The fuel rail pressure sensor detects fuel pressure within the fuel rail. The engine control module (ECM) provides a 5 V reference voltage on the 5 V reference circuit and ground on the low reference circuit. The ECM receives a varying signal voltage on the signal circuit. The ECM monitors the voltage on the fuel rail pressure sensor circuits. When the fuel pressure is high, the signal voltage is high. When the fuel pressure is low, the signal voltage is low.

Conditions for Running the DTC

Condition 1

    • DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0122, P0123, P0201-P0206, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0301-P0306, P0351-P0356, P0506, P0507, P0722, P0723, P1248, P1249, P124A, P124B, P2122, P2123, P2127, P2128, P2135, P2147, P2148, P2150, P2151, P2153, P2154, P2156, or P2157 are not set.
    • The engine is running.
    • The accelerator pedal position is 0 percent for 4 s.
    • The ignition voltage is greater than 11 V.
    • The low side fuel pressure is greater than 275 kPa (40 psi).
    • The vehicle speed is less than 1 km/h (0.62 mph).
    •  The diagnostic runs continuously when the above conditions are met.

Condition 2 and 3

    • DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0122, P0123, P0201-P0206, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0301-P0306, P0351-P0356, P0506, P0507, P0722, P0723, P1248, P1249, P124A, P124B, P2122, P2123, P2127, P2128, P2135, P2147, P2148, P2150, P2151, P2153, P2154, P2156, or P2157 are not set.
    • The ignition voltage is greater than 11 V.
    • The low side fuel pressure is greater than 275 kPa (40 psi).
    • The desired fuel rail pressure is between 4-6 MPa (580-870 psi).
    • The engine speed is between 1000-3000 RPM.
    • The vehicle speed is greater than 30 km/h (18.64 mph).
    •  The diagnostic runs continuously when the above conditions are met.

Condition 4

    • DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0122, P0123, P0201-P0206, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0301-P0306, P0351-P0356, P0506, P0507, P0722, P0723, P1248, P1249, P124A, P124B, P2122, P2123, P2127, P2128, P2135, P2147, P2148, P2150, P2151, P2153, P2154, P2156, or P2157 are not set.
    • The engine speed is greater than 2000 RPM.
    • The vehicle speed is greater than 30 km/h (18.64 mph).
    •  DTC P0191 runs once an ignition cycle at engine start up when the above conditions have been met.

Conditions for Setting the DTC

Condition 1

The difference between the low side fuel pressure and the high side fuel pressure is less than or equal to -0.8 MPa (-116 psi) or greater than or equal to 0.3 MPa (44 psi) with the high pressure fuel pump actuator commanded OFF. The condition exists for greater than 3 s.

Condition 2

The difference between the relief pressure and the measured high pressure is less than or equal to -2 MPa (-290 psi) for greater than 3 s.

Condition 3

The difference between the desired fuel rail pressure and the actual fuel rail pressure is greater than 2 MPa (290 psi) for 3 s.

Condition 4

The difference between the measured maximum high pressure and the measured minimum high pressure is less than or equal to 0.1 MPa (14.5 psi) for greater than 10 s.

Action Taken When the DTC Sets
    • DTC P0191 is a Type A DTC.
    • A message centre or an indicator may display Reduced Engine Power.

Conditions for Clearing the DTC

DTC P0191 is a Type A DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Fuel System Description : LF1

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. Observe the scan tool DTC information, verify DTC P0627, P0628, P0629, P069E or U0109 is not set.
    2. ⇒If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
  2. Engine idling, observe the scan tool Fuel Rail Pressure Sensor parameter. The pressure should be approximately 1.9-5.0 MPa (276-725 psi).
  3. Engine idling, the scan tool Fuel Rail Pressure Sensor should be close to the scan tool Desired Fuel Rail Pressure. As the engine speed increases, the Desired Fuel Rail Pressure and the Fuel Rail Pressure Sensor should closely match each other.
  4. Move related harnesses/connectors of the B47B fuel rail pressure sensor and verify the engine does not stumble, stall, or change engine speed.
    5. ⇒If the engine stumbles, stalls, or changes engine speed, test or repair the suspected harness or connection.
  5. Observe the DTC information with a scan tool, DTC P0191 should not set.
  6. 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 B47B fuel rail pressure sensor connector.
  2. Ignition OFF, and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 Ω between the low reference circuit terminal C and ground.
    3. ⇒If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
  3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal A and ground.
    4. ⇒If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
    ⇒If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
  4. Ignition ON, verify the scan tool Fuel Rail Pressure Sensor voltage parameter is less than 0.02 V.
    5. ⇒If greater than the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
  5. Connect a 3 A fused jumper wire between the signal circuit terminal B and the 5 V reference circuit terminal A. Verify the scan tool Fuel Rail Pressure Sensor Voltage parameter is greater than 4.96 V.
    6. ⇒If less than the specified value, test the signal circuit for an open circuit/high resistance or a short to ground. If the circuit tests normal, replace the K20 ECM.
  6. If all circuits test normal, replace the B47B fuel rail pressure sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Fuel Pressure Sensor Replacement - Fuel Injection Fuel Rail : LF1 or LFW
    • Control Module References for ECM replacement, setup, and programming
   


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