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Home >> Infiniti >> 2019 >> QX60 Pure, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (DTC/Circuit Diagnosis) (4 Of 17) >> DTC/Circuit Diagnosis >> DTC P0128: Thermostat Function >> DTC Confirmation Procedure
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DTC Confirmation Procedure

NOTE: Never refuel before and during the following procedure.
  1. CHECK DTC PRIORITY 

    If DTC P0128 is displayed with DTC P0300, P0301, P0302, P0303, P0304, P0305 or P0306, first perform the confirmation procedure (trouble diagnosis) for DTC P0300, P0301, P0302, P0303, P0304, P0305 or P0306.

    Is DTC P0300, P0301, P0302, P0303, P0304, P0305 or P0306 detected?

    YES

    Perform diagnosis of applicable. Refer to DTC Description .

    NO

    GO TO 2.

  2. PRECONDITIONING-I 

    If DTC Confirmation Procedure has been previously conducted, always perform the following procedure 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.

    GO TO 3.

  3. PRECONDITIONING-II 

    SYMBOL With CONSULT

    1. Turn ignition switch ON.
    2. Check the following conditions:

      Ambient temperature

      -10 deg.C (14 deg.F) or more

      A/C switch

      OFF

      Blower fan switch

      OFF
    3. On CONSULT screen, select "ENGINE">>"Data Monitor">>"COOLANT TEMP/S".
    4. Check the following conditions:

      COOLANT TEMP/S

      -10 deg.C - 55 deg.C (14 - 131 deg.F)

    Is the condition satisfied?

    YES

    GO TO 4.

    NO

    1. Satisfy the condition.
    2. GO TO 4.
  4. PERFORM DTC CONFIRMATION PROCEDURE-I 

    SYMBOL With CONSULT

    1. Start engine.
    2. Drive the vehicle until the following condition is satisfied.
      CAUTION: Always drive vehicle at safe speed.
      1. STEP 1

        Drive the vehicle under the conditions instructed below until the difference between "COOLANT TEMP/S" and "FUEL T/TMP SE" becomes at least 25 deg.C (45 deg.F).

        COOLANT TEMP/S

        74 deg.C (165 deg.F) or less

        FUEL T/TMP SE

        Less than the value calculated by subtracting 25 deg.C (45 deg.F) from "COOLANT TEMP/S".*
        *: Example

        COOLANT TEMP/S

        FUEL T/TMP SE

        70 deg.C (158 deg.F)

        45 deg.C (113 deg.F) or less

        65 deg.C (149 deg.F)

        40 deg.C (104 deg.F) or less

        60 deg.C (140 deg.F)

        35 deg.C (95 deg.F) or less
      2. STEP 2

        Drive the vehicle at 50 km/h (32 MPH) or more with the difference between "COOLANT TEMP/S" and "FUEL T/TMP SE" maintained at 25 deg.C (45 deg.F) or more.

        NOTE: Keep the accelerator pedal as steady as possible during cruising.
      3. STEP 3

        Drive the vehicle at 50 km/h (32 MPH) or more until "COOLANT TEMP/S" increases by 6 deg.C (43 deg.F).

        NOTE: Keep the accelerator pedal as steady as possible during cruising.

    Is the condition satisfied?

    YES

    GO TO 5.

    NO

    GO TO 2.

  5. PERFORM DTC CONFIRMATION PROCEDURE-II 

    SYMBOL With CONSULT

    1. Drive the vehicle until the following condition is satisfied.

      COOLANT TEMP/S

      71 deg.C (160 deg.F) or more
      CAUTION: Always drive vehicle at safe speed.
    2. Check 1st trip DTC.

    Is DTC P0128 detected?

    YES

    Proceed to Diagnosis Procedure .

    NO

    To check malfunction symptom before repair: Refer to Intermittent Incident .

    NO

    Confirmation after repair: INSPECTION END

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