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Home >> Infiniti >> 2014 >> Q60 Base, 2D Convertible, Automatic Trans >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System - DTCS P014C To P0463 (Convertible) >> DTC P0420, P0430: Three Way Catalyst Function >> Diagnosis Procedure
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Diagnosis Procedure

  1. CHECK EXHAUST SYSTEM 

    Visually check exhaust tubes and muffler for dents.

    Is the inspection result normal? 

    YES: GO TO 2.

    NO: Repair or replace.

  2. CHECK EXHAUST GAS LEAK 
    1. Start engine and run it at idle.
    2. Listen for an exhaust gas leak before the three way catalyst 1.
      Fig 1: Identifying Exhaust Leak
      G04875054Courtesy of NISSAN NORTH AMERICA, INC.

      Is exhaust gas leak detected? 

      YES: Repair or replace.

      NO: GO TO 3.

  3. CHECK INTAKE AIR LEAK 

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

    Is intake air leak detected? 

    YES: Repair or replace.

    NO: GO TO 4.

  4. CHECK IDLE SPEED AND IGNITION TIMING 

    For procedure, refer to "BASIC INSPECTION: SPECIAL REPAIR REQUIREMENT ".

    For specification, refer to "IDLE SPEED " and "IGNITION TIMING ".

    Is the inspection result normal? 

    YES: GO TO 5.

    NO: Follow the "BASIC INSPECTION: SPECIAL REPAIR REQUIREMENT ".

  5. CHECK FUEL INJECTORS 
    1. Stop engine and then turn ignition switch ON.
    2. Check the voltage between ECM harness connector terminals as per the following.
      ECM Voltage
      + -
      Connector Terminal Connector Terminal
      F102 81 M107 128 Battery voltage
      82
      85
      86
      89
      90

      Is the inspection result normal? 

      YES: GO TO 6.

      NO: Perform "DIAGNOSIS PROCEDURE ".

  6. CHECK FUNCTION OF IGNITION COIL-I 
    CAUTION: Perform the following procedure in a place where with no combustible objects and good ventilation.
    1. Turn ignition switch OFF.
    2. Remove fuel pump fuse (1) in IPDM E/R (2) 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 two or three 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.
      Fig 2: Identifying Fuel Pump Fuse And IPDM E/R
      G07012274Courtesy of NISSAN NORTH AMERICA, INC.
    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 the figure below.
    11. Crank engine for about 3 seconds, and check whether spark is generated between the spark plug and the grounded metal portion.

      Spark should be generated. 

      Fig 3: Checking For Spark
      G07012275Courtesy of NISSAN NORTH AMERICA, INC.
      CAUTION:
      • During the operation, always stay 0.5 m (1.6 ft) or more away from the spark plug and ignition coil. Be careful not to get an electrical shock while checking, because the electrical discharge voltage becomes 20 kV or more.
      • It might damage the ignition coil if the gap of more than 17 mm (0.66 in) is made.
      NOTE: When the gap is less than 13 mm (0.52 in), a spark might be generated even if the coil is malfunctioning.

      Is the inspection result normal? 

      YES: GO TO  10.

      NO: GO TO 7.

  7. CHECK FUNCTION OF IGNITION COIL-II 
    1. Turn ignition switch OFF.
    2. Disconnect spark plug and connect a non-malfunctioning spark plug.
    3. Crank engine for about 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 8.

      NO: Check ignition coil, power transistor and their circuits. Refer to "DIAGNOSIS PROCEDURE ".

  8. CHECK SPARK PLUG 

    Check the initial spark plug for fouling, etc.

    Is the inspection result normal? 

    YES: Replace spark plug(s) with standard type one(s). For spark plug type, refer to "INSPECTION ".

    NO: Repair or clean spark plug. Then GO TO 9.

    Fig 4: Identifying Initial Spark Plug For Fouling
    G04875165Courtesy of NISSAN NORTH AMERICA, INC.
  9. CHECK FUNCTION OF IGNITION COIL-III 
    1. Reconnect the initial spark plugs.
    2. Crank engine for about three 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 "REMOVAL AND INSTALLATION ".

  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 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 11.

  11. CHECK INTERMITTENT INCIDENT 

    Refer to "INTERMITTENT INCIDENT ".

    Is the inspection result normal? 

    YES: Replace three way catalyst assembly. Refer to "EXPLODED VIEW ".

    NO: Repair or replace harness or connector.