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Home >> Infiniti >> 2015 >> QX60 Base, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 117 (Engine Control System (DTC/Circuit Diagnosis) (VQ35DE) (Except Hybrid) (2 Of 3)) >> DTC/Circuit Diagnosis >> DTC P0420, P0430: Three Way Catalyst Function >> Diagnosis Procedure >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2016 Infiniti QX60. However, it is still accessible from the selected car via links, so may be relevant.

  1. CHECK EXHAUST SYSTEM

    Visually check exhaust tubes and muffler for dents.

    Is the inspection result normal?

    YES 

    GO TO STEP 2  .

    NO 

    Repair or replace malfunctioning part.

  2. CHECK EXHAUST GAS LEAKAGE

    1. Start engine and run it at idle.
    2. Listen for an exhaust gas leakage before the three way catalyst (manifold).
      G04191081Courtesy of NISSAN NORTH AMERICA, INC.

    Is exhaust gas leakage detected?

    YES 

    Repair or replace malfunctioning part.

    NO 

    GO TO STEP 3. 

  3. CHECK INTAKE AIR LEAKAGE

    Listen for an intake air leakage after the mass air flow sensor.

    Is intake air leakage detected?

    YES 

    Repair or replace malfunctioning part.

    NO 

    GO TO STEP 4. 

  4. CHECK IGNITION TIMING

    Check idle speed and ignition timing.

    For procedure, refer to WORK PROCEDURE .

    For specification, refer to IDLE SPEED and IGNITION TIMING .

    Is the inspection result normal?

    YES 

    GO TO STEP 5  .

    NO 

    Follow the WORK PROCEDURE .

  5. CHECK FUEL INJECTORS

    1. Stop engine and then turn ignition switch ON.
    2. Check the voltage between ECM harness connector terminals.
      ECM Voltage
      + -
      Connector Terminal Connector Terminal
      F78 11 E32 152 Battery voltage
      12
      16
      17
      21
      22

    Is the inspection result normal?

    YES 

    GO TO STEP 6  .

    NO 

    Perform DIAGNOSIS PROCEDURE .

  6. CHECK FUNCTION OF IGNITION COIL-I

    CAUTION:

    Perform the following procedure in a place with no combustible objects and good ventilation.

    1. Turn ignition switch OFF.
    2. Remove fuel pump fuse in IPDM E/R to release fuel pressure.
      NOTE:

      Do not use CONSULT to release fuel pressure, or fuel pressure applies again during the following procedure.

    3. Start engine.
    4. After engine stalls, crank it 2 or 3 times to release all fuel pressure.
    5. Turn ignition switch OFF.
    6. Remove all ignition coil harness connectors to avoid the electrical discharge from the ignition coils.
    7. Remove ignition coil and spark plug of the cylinder to be checked.
    8. Crank engine for 5 seconds or more to remove combustion gas in the cylinder.
    9. Connect spark plug and harness connector to ignition coil.
    10. Fix ignition coil using a rope etc. with gap of 13 - 17 mm (0.52 - 0.66 in) between the edge of the spark plug and grounded metal portion as shown in illustration.
      G04886523Courtesy of NISSAN NORTH AMERICA, INC.
    11. Crank engine for approximately 3 seconds, and check whether spark is generated between the spark plug and the grounded metal portion.
      Spark should be generated.
      CAUTION:
      • During the operation, always stay 0.5 m (19.7 in) or more away from the spark plug and the ignition coil. Be careful not to get an electrical shock while checking, because the electrical discharge voltage becomes 20 kV or more.
      • It might cause to damage the ignition coil if the gap of more than 17 mm (0.66 in) is taken.
      NOTE:

      When the gap is less than 13 mm (0.52 in), the spark might be generated even if the coil is malfunctioning. 

    Is the inspection result normal?

    YES 

    GO TO STEP   10  .

    NO 

    GO TO STEP 7  .

  7. CHECK FUNCTION OF IGNITION COIL-II

    1. Turn ignition switch OFF.
    2. Disconnect spark plug and connect a known-good spark plug.
    3. Crank engine for approximately 3 seconds, and recheck whether spark is generated between the spark plug and the grounded metal portion.
      Spark should be generated.

    Is the inspection result normal?

    YES 

    GO TO STEP 8  .

    NO 

    Check ignition coil, power transistor and their circuit. Refer to DIAGNOSIS PROCEDURE .

  8. CHECK SPARK PLUG

    Check the initial spark plug for fouling, etc.

    G04185314Courtesy of NISSAN NORTH AMERICA, INC.

    Is the inspection result normal?

    YES 

    Replace spark plug(s) with standard type one(s). For spark plug type, refer to SPARK PLUG .

    NO 

    Repair or clean spark plug. Then GO TO STEP 9. 

  9. CHECK FUNCTION OF IGNITION COIL-III

    1. Reconnect the initial spark plugs.
    2. Crank engine for approximately 3 seconds, and recheck whether spark is generated between the spark plug and the grounded portion.
      Spark should be generated.

    Is the inspection result normal?

    YES 

    INSPECTION END

    NO 

    Replace spark plug(s) with standard type one(s). For spark plug type, refer to SPARK PLUG .

  10. CHECK FUEL INJECTOR

    1. Turn ignition switch OFF.
    2. Remove fuel injector assembly. Refer to REMOVAL AND INSTALLATION .

      Keep fuel hose and all fuel injectors connected to fuel tube.

    3. Disconnect all ignition coil harness connectors.
    4. Reconnect all fuel injector harness connectors disconnected.
    5. Turn ignition switch ON.
    6. Check that the fuel does not drip from fuel injector.

    Does fuel drip from fuel injector?

    YES 

    Replace the fuel injector(s) from which fuel is dripping. Refer to REMOVAL AND INSTALLATION .

    NO 

    GO TO STEP 11  .

  11. CHECK INTERMITTENT INCIDENT

    Check intermittent incident. Refer to INTERMITTENT INCIDENT .

    Is the inspection result normal?

    YES 

    Replace three way catalyst assembly. Refer to REMOVAL AND INSTALLATION (BANK 2) , REMOVAL AND INSTALLATION (BANK 1) .

    NO 

    Repair or replace error-detected parts.

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