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Home >> Nissan-Datsun >> 2012 >> Quest LE >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - DTCS P014C To P0453 >> DTC P0420, P0430: Three Way Catalyst Function >> Diagnosis Procedure

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 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).
      Fig 1: Checking Exhaust Gas Leakage
      G08171534Courtesy of NISSAN NORTH AMERICA, INC.

      Is exhaust gas leakage detected? 

      YES: Repair or replace malfunctioning part.

      NO: GO TO 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 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 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
      F7 33 E16 128 Battery voltage
      44
      45
      46
      47
      48

      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 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 the figure below.
    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. 

      Fig 2: Checking For Spark
      G08171535Courtesy of NISSAN NORTH AMERICA, INC.
      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  10.

      NO: GO TO 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 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.

    Is the inspection result normal? 

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

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

    Fig 3: Checking Spark Plug
    G08171536Courtesy of NISSAN NORTH AMERICA, INC.
  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: SPARK PLUG ".

  10. CHECK FUEL INJECTOR
    1. Turn ignition switch OFF.
    2. Remove fuel injector assembly. Refer to "EXPLODED VIEW ".

      Refer to "EXPLODED VIEW ".

      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 "EXPLODED VIEW ".

      NO: GO TO 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 "EXPLODED VIEW ".

    NO: Repair or replace error-detected parts.