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Home >> Infiniti >> 2024 >> QX80 Premium Select, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (DTCS) (2 Of 4) >> Engine (ECM) >> DTC P0420: Three Way Catalyst Function >> Confirmation Procedure
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Confirmation Procedure

  1. INSPECTION START 
    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.

    Will CONSULT be used?

    YES>>

    GO TO 2.

    NO>>

    GO TO 6.

  2. PERFORM DTC CONFIRMATION PROCEDURE-I SYMBOL

    TESTING CONDITION:

    Do not maintain engine speed for more than the specified minutes below.

    1. Start engine and warm it up to the normal operating temperature.
    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 3500 and 4000 RPM for at least 1 minute under no load.
    6. Let engine idle for 1 minute.
    7. Select "DATA MONITOR" mode with CONSULT.
    8. Check that "COOLAN TEMP/S" indicates more than 70°C (158°F).

      If not, warm up engine and go to next step when "COOLAN TEMP/S" indication reaches to 70°C (158°F).

    9. Open engine hood.
    10. Select "DTC and SRT CONFIRMATION" then "SRT WORK SUPPORT" mode with CONSULT.
    11. Rev engine between 2, 000 and 3, 000 RPM and hold it for 3 consecutive minutes then release the accelerator pedal completely.
    12. Check the indication of "CATALYST".

    Which is displayed on CONSULT screen?

    CMPLT>>

    GO TO 5.

    INCMP>>

    GO TO 3.

  3. PERFORM DTC CONFIRMATION PROCEDURE-II 
    1. Wait 5 seconds at idle.
    2. Rev engine between 2, 000 and 3, 000 RPM and maintain it until "INCMP" of "CATALYST" changes to "CMPLT" (It will take approximately 5 minutes).

    Does the indication change to "CMPLT"?

    YES>>

    GO TO 5.

    NO>>

    GO TO 4.

  4. PERFORM DTC CONFIRMATION PROCEDURE AGAIN 
    1. Stop engine and cool it down to less than 70°C (158°F).
    2. Perform DTC CONFIRMATION PROCEDURE again.

    >>

    GO TO 2.

  5. PERFORM DTC CONFIRMATION PROCEDURE-III 

    Check 1st trip DTC.

    Is 1st trip DTC detected?

    YES>>

    Refer to DTC Diagnosis Procedure .

    NO>>

    INSPECTION END

  6. PERFORM COMPONENT FUNCTION CHECK SYMBOL
    NOTE: Use component function check to check the overall function of the three way catalyst (manifold). During this check, a 1st trip DTC might not be confirmed.
    1. Start engine and warm it up to the normal operating temperature.
    2. Turn ignition switch OFF and wait at least 10 seconds.
    3. Start engine and keep the engine speed between 3500 and 4000 RPM for at least 1 minute under no load.
    4. Let engine idle for 1 minute.
    5. Open engine hood.
    6. Check the voltage between ECM harness connector terminals under the following conditions.
      DTC ECM Condition Voltage
      + -
      Connector Terminal Connector Terminal
      P0420 F92 84
      [HO2S2 (bank 1)]      		 F91 43 Keeping engine speed at 2, 500 RPM constant under no load The voltage fluctuation cycle takes more than 5 seconds.
      • 1 cycle: 0.6 - 1.0 → 0 - 0.3 → 0.6 - 1.0
      P0430 77
      [HO2S2 (bank 2)]

    Is the inspection result normal?

    YES>>

    INSPECTION END

    NO>>

    Refer to DTC Diagnosis Procedure .

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