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Home >> Infiniti >> 2021 >> Q50 Pure, AWD >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System (DTCS) (2 Of 6) >> Engine (ECM) >> P0174 Fuel Injection System Function >> DTC Diagnosis Procedure >> VR30DDTT engine
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VR30DDTT engine

  1. CHECK EXHAUST GAS LEAK 
    1. Start engine and run it at idle.
    2. Listen for an exhaust gas leak before three way catalyst 1.
      G04073923Courtesy of NISSAN NORTH AMERICA, INC.

    Is exhaust gas leak detected?

    YES

    Repair or replace error-detected parts.

    NO

    GO TO 2.

  2. CHECK FOR INTAKE AIR LEAK 
    1. Listen for an intake air leak after the mass air flow sensor.
    2. Check PCV hose connection.

    Is intake air leak detected?

    YES

    Repair or replace error-detected parts.

    NO

    GO TO 3.

  3. CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect corresponding A/F sensor 1 harness connector.
    3. Disconnect ECM harness connector.
    4. Check the continuity between A/F sensor 1 harness connector and ECM harness connector.

      +

      -

      Continuity

      A/F sensor 1

      ECM

      Bank

      Connector

      Terminal

      Connector

      Terminal

      2

      F134

      3

      F142

      106

      Existed

      4

      105

    5. Check the continuity between A/F sensor 1 harness connector and ground, or ECM harness connector and ground.

      +

      -

      Continuity

      A/F sensor 1

      Bank

      Connector

      Terminal

      2

      F134

      3

      Ground

      Not existed

      4

      +

      -

      Continuity

      ECM

      Bank

      Connector

      Terminal

      2

      F142

      105

      Ground

      Not existed

      106

    6. Also check harness for short to power.

    Is the inspection result normal?

    YES

    GO TO 4.

    NO

    Repair or replace error-detected parts.

  4. CHECK A/F SENSOR 1 FUNCTION CHECK-1 

    If DTC Confirmation Procedure has been previously conducted, always perform the following before conducting the next test.

    1. Turn ignition switch OFF and wait at least 10 seconds.
    2. Turn ignition switch ON.
    3. Turn ignition switch OFF and wait at least 10 seconds.

    TESTING CONDITION:

    Before performing the following procedure, confirm that battery voltage is more than 11 V at idle.

    GO TO 5.

  5. CHECK A/F SENSOR 1 FUNCTION CHECK-2 
    1. Clear the mixture ratio self-learning value. Refer to Description.
    2. Turn ignition switch OFF and wait at least 10 seconds.
    3. Turn ignition switch ON.
    4. Turn ignition switch OFF and wait at least 10 seconds.
    5. Start engine and keep the engine speed between 3, 500 and 4, 000 RPM for 1 minute under no load.
    6. Let engine idle for 1 minute.
    7. Keep engine speed between 2, 500 and 3, 000 RPM for 20 minutes.
    8. Check DTC.

    Is DTC detected?

    YES

    Replace A/F sensor. Refer to TURBOCHARGER : Removal & Installation .

    NO

    GO TO 6.

  6. CHECK FUEL PRESSURE 

    Check fuel pressure. Refer to Work Procedure .

    Is the inspection result normal?

    YES

    GO TO 8.

    NO

    GO TO 7.

  7. DETECT MALFUNCTIONING PART 

    Check fuel hoses and fuel tubes for clogging.

    Is the inspection result normal?

    YES

    Replace "fuel filter and fuel pump assembly". Refer to FUEL LEVEL SENSOR UNIT, FUEL FILTER AND FUEL PUMP ASSEMBLY : Removal & Installation .

    NO

    Repair or replace error-detected parts.

  8. CHECK MASS AIR FLOW SENSOR 

    SYMBOL With CONSULT

    1. Install all removed parts.
    2. Check "MASS AIR FLOW SENSOR (Hz)" in "DATA MONITOR" mode with CONSULT.

      For specification, Refer to MASS AIR FLOW SENSOR : Service Data .

    SYMBOL With GST

    1. Install all removed parts.
    2. Check mass air flow sensor signal in Service $01 with GST.

      For specification, Refer to MASS AIR FLOW SENSOR : Service Data .

    Is the measurement value within the specification?

    YES

    GO TO 9.

    NO

    Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or grounds. Refer to DTC Diagnosis Procedure .

  9. CHECK FUNCTION OF FUEL INJECTOR 

    SYMBOL With CONSULT

    1. Start engine.
    2. Perform "POWER BALANCE" in "ACTIVE TEST" mode with CONSULT.
    3. Make sure that each circuit produces a momentary engine speed drop.

    SYMBOL Without CONSULT

    1. Start engine and let it idle.
    2. Listen to each fuel injector operating sound.
      G04812223Courtesy of NISSAN NORTH AMERICA, INC.

      Clicking sound should be heard.

    Is the inspection result normal?

    YES

    INSPECTION END

    NO

    Perform trouble diagnosis for FUEL INJECTOR, Refer to Diagnosis Procedure .