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HOMESERVICE MANUALSINFINITI2019Q70 3.7 LUXE, AWDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 6 (ENGINE CONTROL SYSTEM (5.6L) (DTC/CIRCUIT DIAGNOSIS) (4 OF 9))DTC/CIRCUIT DIAGNOSISDTC P0451: EVAP CONTROL SYSTEM PRESSURE SENSORDIAGNOSIS PROCEDURE
2019 Infiniti Q70 3.7 Luxe, AWD

Diagnosis Procedure

2019 Infiniti Q70 3.7 Luxe, AWDSECTION Diagnosis Procedure
WARNING: This page is about a different variant/trim than selected.
  1. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR CONNECTOR 
    1. Disconnect EVAP control system pressure sensor harness connector.
    2. Check that water is not inside connectors.

    Is the inspection result normal?

    YES

    GO TO 2.

    NO

    Repair or replace harness connector.

  2. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR POWER SUPPLY CIRCUIT 
    1. Turn ignition switch ON.
    2. Check the voltage between EVAP control system pressure sensor harness connector and ground.

      EVAP control system pressure sensor

      Ground

      Voltage (V)

      Connector

      Terminal

      B73

      3

      Ground

      Approx. 5 V

    Is the inspection result normal?

    YES

    GO TO 5.

    NO

    GO TO 3.

  3. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR POWER SUPPLY CIRCUIT II 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check the continuity between EVAP control system pressure sensor harness connector and ECM harness connector.

      EVAP control system pressure sensor

      ECM

      Continuity

      Connector

      Terminal

      Connector

      Terminal

      B73

      3

      M56

      125

      Existed

    Is the inspection result normal?

    YES

    GO TO 5.

    NO

    GO TO 4.

  4. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness for open between ECM and EVAP control system pressure sensor
    • Loose or poor connection for each connector and harness

    Repair open circuit.

  5. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR GROUND CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check the continuity between EVAP control system pressure sensor harness connector and ECM harness connector.

      EVAP control system pressure sensor

      ECM

      Continuity

      Connector

      Terminal

      Connector

      Terminal

      B73

      1

      M56

      148

      Existed
    4. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    YES

    GO TO 7.

    NO

    GO TO 6.

  6. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness for open or short between EVAP control system pressure sensor and ECM
    • Loose or poor connection for each connector and harness

    Repair open circuit, short to ground or short to power in harness or connectors.

  7. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    1. Check the continuity between EVAP control system pressure sensor harness connector and ECM harness connector.

      EVAP control system pressure sensor

      ECM

      Continuity

      Connector

      Terminal

      Connector

      Terminal

      B73

      2

      M56

      121

      Existed
    2. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    YES

    GO TO 9.

    NO

    GO TO 8.

  8. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness for open or short between EVAP control system pressure sensor and ECM
    • Loose or poor connection for each connector and harness

    Repair open circuit, short to ground or short to power in harness or connectors.

  9. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR 

    Refer to Component Inspection (EVAP Control System Pressure Sensor) .

    Is the inspection result normal?

    YES

    GO TO 10.

    NO

    Replace EVAP control system pressure sensor. Refer to Exploded View .

  10. CHECK INTERMITTENT INCIDENT 

    Refer to Intermittent Incident .

    INSPECTION END

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.