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Home >> Infiniti >> 2005 >> G35 x >> Repair and Diagnosis >> Engine Performance >> Engine Control System - Sedan >> DTC P0172, P0175: Fuel Injection System Function >> Diagnostic Procedure
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Diagnostic Procedure

  1. CHECK EXHAUST GAS LEAK 
    1. Start engine and run it at idle.
    2. Listen for an exhaust gas leak before three way catalyst 1.
      Fig 1: Checking For Exhaust Gas Leak
      G02348479Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

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

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

    OK or NG 

    1. OK: GO TO 3.
    2. NG: Repair or replace.
  3. CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect corresponding A/F sensor 1 harness connector.
      Fig 2: Disconnecting Corresponding A/F Sensor 1 Harness Connector
      G02348480Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Disconnect ECM harness connector.
    4. Check harness continuity between the following terminals. Refer to Wiring Diagram.
      Fig 3: Continuity Harness Checking Table
      G02348481Courtesy of NISSAN MOTOR CO., U.S.A.

      Continuity should exist. 

    5. Check harness continuity between the following terminals and ground. Refer to Wiring Diagram.
      Fig 4: Continuity Harness Checking Table
      G02348482Courtesy of NISSAN MOTOR CO., U.S.A.

      Continuity should not exist. 

    6. Also check harness for short to power.

    OK or NG 

    1. OK: GO TO 4.
    2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
  4. CHECK FUEL PRESSURE 
    1. Release fuel pressure to zero. Refer to "FUEL PRESSURE RELEASE ".
    2. Install fuel pressure gauge and check fuel pressure. Refer to "FUEL PRESSURE CHECK ".

      At idling: Approximately 350 kPa (3.57 kg/cm 2  , 51 psi) 

    OK or NG 

    1. OK: GO TO  6.
    2. NG: GO TO 5.
  5. DETECT MALFUNCTIONING PART 

    Check the following.

    1. : Repair or replace.
  6. CHECK MASS AIR FLOW SENSOR 

    With CONSULT-II 

    1. Install all removed parts.
    2. Check "MASS AIR FLOW" in "DATA MONITOR" mode with CONSULT-II.

      2.0 - 6.0 g.m/sec: at idling 

      7.0 - 20.0 g.m/sec: at 2,500 RPM 

    With GST 

    1. Install all removed parts.
    2. Check mass air flow sensor signal in Service $01 with GST.

      2.0 - 6.0 g.m/sec: at idling 

      7.0 - 20.0 g.m/sec: at 2,500 RPM 

    OK or NG 

    1. OK (With CONSULT-II): GO TO 7.
    2. OK (Without CONSULT-II): GO TO  8.
    3. NG: Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or ground. Refer to "DTC P0101 MAF SENSOR ".
  7. CHECK FUNCTION OF INJECTOR 

    With CONSULT-II 

    1. Start engine.
    2. Perform "POWER BALANCE" in "ACTIVE TEST" mode with CONSULT-II.
    3. Make sure that each circuit produces a momentary engine speed drop.
      Fig 5: Locating Active Test Display Screen
      G02348483Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO  10.
    2. NG: Perform trouble diagnosis for INJECTOR CIRCUIT, "INJECTOR CIRCUIT ".
  8. CHECK FUNCTION OF INJECTOR-I 

    Without CONSULT-II 

    1. Stop engine.
    2. Disconnect harness connector F33, F221
    3. Turn ignition switch ON.
      Fig 6: Locating Harness Connector
      G02348484Courtesy of NISSAN MOTOR CO., U.S.A.
    4. Check voltage between harness connector F33 terminal 5 and ground with CONSULT-II or tester.

      Voltage: Battery voltage 

    5. Turn ignition switch OFF.
    6. Disconnect ECM harness connector.
    7. Check harness continuity between harness connector F33 and ECM as follows.

      Refer to Wiring Diagram

      Fig 7: Checking Voltage Between Harness Connector F33 Terminal 5 & Ground
      G02348485Courtesy of NISSAN MOTOR CO., U.S.A.
      HARNESS CONNECTOR F33 TERMINAL 5 VOLTAGE CHECK

      Cylinder Harness connector F33 terminal ECM terminal
      1 6 23
      2 4 42
      3 2 22
      4 3 41
      5 1 21
      6 7 40

      Continuity should exist. 

    8. Also check harness for short to ground and short to power.

    OK or NG 

    1. OK: GO TO 9.
    2. NG: Perform trouble diagnosis for INJECTOR CIRCUIT, refer to "INJECTOR CIRCUIT ".
  9. CHECK FUNCTION OF INJECTOR-II 

    Provide battery voltage between harness connector F221 as follows and then interrupt it. Listen to each injector operating sound.

    Fig 8: Voltage Table Of Battery Harness Connector
    G02348486Courtesy of NISSAN MOTOR CO., U.S.A.
    Fig 9: Providing Battery Voltage Between Harness Connector F221
    G02348487Courtesy of NISSAN MOTOR CO., U.S.A.

    Operating sound should exist. 

    OK or NG 

    1. OK: GO TO 10.
    2. NG: Perform trouble diagnosis for INJECTOR CIRCUIT, refer to "INJECTOR CIRCUIT ".
  10. CHECK INJECTOR 
    1. Remove injector assembly. Refer to "FUEL INJECTOR AND FUEL TUBE ".

      Keep fuel hose and all injectors connected to injector gallery.

    2. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
    3. Reconnect all harness connectors disconnected.
    4. Disconnect all injector harness connectors.
    5. Disconnect all ignition coil harness connectors.
    6. Prepare pans or saucers under each injectors.
    7. Crank engine for about 3 seconds.

      Make sure fuel does not drip from injector

    OK or NG 

    1. OK (Does not drip.): GO TO 11.
    2. NG (Drips.): Replace the injectors from which fuel is dripping. Always replace O-ring with new one.
  11. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    1. :INSPECTION END 
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