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Home >> Nissan-Datsun >> 2007 >> X-Trail LE >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - DTCS P0171 To P0453 >> DTC P0420 Three Way Catalyst Function >> Diagnostic Procedure

Diagnostic Procedure

  1. CHECK EXHAUST SYSTEM 

    Visually check exhaust tubes and muffler for dent.

    OK or NG 

    OK: GO TO 2.

    NG: 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 (manifold).
    Fig 1: Checking Exhaust Gas Leakage
    G06152590Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO 3.

    NG: Repair or replace.

  3. CHECK INTAKE AIR LEAK 

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

    OK or NG 

    OK: GO TO 4.

    NG: Repair or replace.

  4. CHECK IGNITION TIMING 

    Check for ignition timing. Refer to "BASIC INSPECTION ".

    ITEM SPECIFICATION

    Items Specifications
    Target idle speed A/T 700 ± 50 rpm (in P or N position)
    M/T 700 ± 50 rpm (in Neutral position)
    Ignition timing A/T 15 ± 5° BTDC (in P or N position)
    M/T 15 ± 5° BTDC (in Neutral position)

    OK or NG 

    OK: GO TO 5.

    NG: Follow the "BASIC INSPECTION ".

  5. CHECK INJECTOR 
    1. Refer to WIRING DIAGRAM  for Injectors, WIRING DIAGRAM .
    2. Stop engine and then turn ignition switch ON.
    3. Check voltage between ECM terminals 22, 23, 41, 42 and ground with CONSULT-II or tester.

      Voltage: Battery voltage 

    Fig 2: Checking Voltage Between ECM Terminals 22, 23, 41, 42 And Ground
    G06152591Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO 6.

    NG: Perform "DIAGNOSTIC PROCEDURE ".

  6. CHECK FUNCTION OF IGNITION COIL-I 
    CAUTION: Do the following procedure in the place where ventilation is good without the combustible.
    1. Turn ignition switch OFF.
    2. Remove fuel pump fuse located in fuse box to release fuel pressure.
      NOTE: Do not use CONSULT-II to release fuel pressure, or fuel pressure applies again during the following procedure.
      Fig 3: Identifying Fuel Pump Fuse (15A) And Fuse Block (J/B)
      G06152551Courtesy of NISSAN MOTOR CO., U.S.A.
    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 between the edge of the spark plug and grounded metal portion as shown in illustration.
    11. Crank engine for about three seconds, and check whether spark is generated between the spark plug and the grounded metal portion.

      Spark should be generated. 

      CAUTION:
      • Do not approach to the spark plug and the ignition coil within 50cm. Be careful not to get an electrical shock while checking, because the electrical discharge voltage becomes 20kV or more.
      • It might cause to damage the ignition coil if the gap of 17 mm or more is taken.
      Fig 4: Identifying Spark Plug And Grounded Metal Portion
      G06152552Courtesy of NISSAN MOTOR CO., U.S.A.
      NOTE: When the gap is 13 mm or less, the spark might be generated even if the coil is malfunctioning.

    OK or NG 

    OK: GO TO  10.

    NG: 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 about 3 seconds, and recheck whether spark is generated between the spark plug and the grounded metal portion.

      Spark should be generated. 

    OK or NG 

    OK: GO TO 8.

    NG: Check ignition coil, power transistor and their circuits. Refer to IGNITION SIGNAL .

  8. CHECK SPARK PLUG 

    Check the spark plugs and check for fouling, etc.

    Fig 5: Identifying Spark Plug
    G06152594Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO 9.

    NG: Repair or replace spark plug (s) with standard type one (s). For spark plug type ignition coil. Refer to "CHANGING SPARK PLUGS (PLATINUM-TIPPED TYPE) ".

  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. 

    OK or NG 

    OK: INSPECTION END 

    NG: Replace spark plug(s) with standard type one(s). For spark plug type, refer to "CHANGING SPARK PLUGS (PLATINUM-TIPPED TYPE) ".

  10. CHECK INJECTOR 
    1. Turn ignition switch OFF.
    2. Remove injector assembly. Refer to "FUEL INJECTOR AND FUEL TUBE ".

      Keep fuel hose and all injectors connected to injector gallery.

    3. Disconnect ignition coil assembly harness connector.
    4. Reconnect all injector harness connectors disconnected.
    5. Turn ignition switch ON.

      Make sure fuel does not drip from injector.

    OK or NG 

    OK (Does not drip): GO TO 11.

    NG (Drips): Replace the injector(s) from which fuel is dripping.

  11. CHECK INTERMITTENT INCIDENT 

    Perform "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    Trouble is fixed: INSPECTION END 

    Trouble is not fixed: Replace three way catalyst (manifold).

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