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Home › Nissan-Datsun › 2004 › Pathfinder SE, RWD › Repair and Diagnosis › Engine Performance › System › Engine Control System › DTC P0420, P0430: Three Way Catalyst › Diagnostic Procedure

Diagnostic Procedure

  1. CHECK EXHAUST SYSTEM 

    Visually check exhaust tubes and muffler for dent.

    OK or NG 

    1. OK: GO TO 2.
    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: Identifying Exhaust Gas Leak Before Three Way Catalyst
    G00336560Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 3.
    2. NG: Repair or replace.
  3. CHECK INTAKE AIR LEAK 

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

    OK or NG 

    1. OK: GO TO 4.
    2. NG: Repair or replace.
  4. CHECK IGNITION TIMING 

    Check the following items. Refer to "BASIC INSPECTION  " .

    Fig 2: Ignition Timing Specification Chart
    G00336561Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 5.
    2. NG: Follow the "Basic Inspection".
  5. CHECK INJECTORS 
    1. Refer to WIRING DIAGRAM  for Injectors .
    2. Stop engine and then turn ignition switch "ON".
    3. Check voltage between ECM terminals 21, 22, 23, 40, 41, 42 and ground with CONSULT-II or tester.
    Fig 3: Checking Voltage Between ECM Terminals 21, 22, 23, 40, 41, 42 And Ground
    G00336562Courtesy of NISSAN MOTOR CO., U.S.A.

    Voltage: Battery voltage 

    OK or NG 

    1. OK: GO TO 6.
    2. NG: Perform "DIAGNOSTIC PROCEDURE  ", "INJECTOR  " .
  6. CHECK IGNITION SPARK 
    1. Turn ignition switch "OFF".
    2. Disconnect ignition coil assembly from rocker cover.
    3. Connect a known-good spark plug to the ignition coil assembly.
    4. Place end of spark plug against a suitable ground and crank engine.
    5. Check for spark.
    Fig 4: Checking Ignition Spark
    G00336563Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 7.
    2. NG: Check ignition coil with power transistor and their circuit. Refer to IGNITION COIL & POWER TRANSISTOR  .
  7. CHECK INJECTOR 
    1. Turn ignition switch "OFF".
    2. Remove injector assembly.

      Refer to REMOVAL AND INSTALLATION  .

      Keep fuel hose and all injectors connected to injector gallery.

    3. Disconnect all ignition coil harness connectors.
    4. Turn ignition switch "ON".

      Make sure fuel does not drip from injector.

    OK or NG 

    1. OK: (Does not drip.) GO TO 8.
    2. NG: (Drips.) Replace the injector(s) from which fuel is dripping.
  8. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT  " .

    1. Trouble is fixed. INSPECTION END 
    2. Trouble is not fixed. Replace three way catalyst (manifold).
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