LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Nissan-Datsun >> 2005 >> Pathfinder LE, RWD >> Repair and Diagnosis >> Engine Performance >> Engine Control System >> DTC P0171, P0174: Fuel Injection System Function >> Diagnostic Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

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 (manifold).
      Fig 1: Checking Exhaust Gas Leakage
      G02431761Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    • OK: GO TO 2.
    • NG: Repair or replace.
  2. CHECK FOR INTAKE AIR LEAK 
    1. Listen for an intake air leak after the mass air flow sensor.
    2. Check PCV hose connection.

    OK or NG 

    • OK: GO TO 3.
    • 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: Locating A/F Sensor 1 Harness Connectors
      G02431762Courtesy 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: ECM Terminal And A/F Sensor 1 Terminal Reference Chart
      G02431763Courtesy of NISSAN MOTOR CO., U.S.A.
      • Continuity should exist. 
    5. Check harness continuity between the following terminals and ground. Refer to ECM TERMINAL AND A/F SENSOR 1 TERMINAL REFERENCE (BANK 1 AND BANK 2)  table.

      Refer to WIRING DIAGRAM .

      ECM TERMINAL AND A/F SENSOR 1 TERMINAL REFERENCE (BANK 1 AND BANK 2)

      Bank 1 Bank 2
      A/F sensor 1 terminal ECM terminal A/F sensor 1 terminal ECM terminal
      1 16 1 76
      2 75 2 77
      5 35 5 57
      6 56 6 58
      • Continuity should not exist. 
    6. Also check harness for short to power.

    OK or NG 

    • OK: GO TO 4.
    • 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: 350 kPa (3.57 kg/cm 2  , 51 psi) 

    OK or NG 

    • OK (With CONSULT-II): GO TO  6.
    • OK (Without CONSULT-II): GO TO  7.
    • NG: GO TO 5.
  5. DETECT MALFUNCTIONING PART 

    Check the following.

    • 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 

    OK or NG 

    • OK: GO TO  8.
    • 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 MASS AIR FLOW SENSOR 

    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 

    • OK (P0171): GO TO  9.
    • OK (P0174): GO TO  11.
    • NG: Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or ground. Refer to DTC P0101 MAF SENSOR .
  8. 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 4: CONSULT-II Display - Active Test Mode
      G02431764Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    • OK: GO TO  12.
    • NG: Perform trouble diagnosis for INJECTOR CIRCUIT, refer to INJECTOR CIRCUIT .
  9. CHECK FUNCTION OF INJECTOR-I 

    Without CONSULT-II 

    1. Stop engine.
    2. Disconnect harness connector F44, F101
      Fig 5: Disconnecting Harness Connector F44 And F101
      G02431765Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Turn ignition switch ON.
    4. Check voltage between harness connector F44 terminal 3 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 F44 and ECM as described in HARNESS CONNECTOR F44 TERMINALS AND ECM TERMINAL REFERENCE  table.

      Refer to WIRING DIAGRAM .

      Fig 6: Checking Voltage Between Harness Connector F44 Terminal 3 And Ground
      G02431766Courtesy of NISSAN MOTOR CO., U.S.A.
      HARNESS CONNECTOR F44 TERMINALS AND ECM TERMINAL REFERENCE

      Cylinder Harness connector F44 terminal ECM terminal
      1 2 23
      2 1 22
      3 4 21
      • Continuity should exist. 
    8. Also check harness for short to ground and short to power.

    OK or NG 

    • OK: GO TO 10.
    • NG: Perform trouble diagnosis for INJECTOR CIRCUIT, refer to INJECTOR CIRCUIT .
  10. CHECK FUNCTION OF INJECTOR-II 

    Provide battery voltage between harness connector F101 as follows and then interrupt it. Listen to each injector operating sound.

    Fig 7: Cylinder No. And Harness Connector F101 Terminal Reference Chart
    G02431767Courtesy of NISSAN MOTOR CO., U.S.A.
    Fig 8: Applying Battery Voltage Between Harness Connector F101 Terminals
    G02431768Courtesy of NISSAN MOTOR CO., U.S.A.
    • Operating sound should exist. 

    OK or NG 

    • OK: GO TO  12.
    • NG: Perform trouble diagnosis for INJECTOR CIRCUIT, refer to INJECTOR CIRCUIT .
  11. CHECK FUNCTION OF INJECTOR 
    1. Start engine.
    2. Listen to injectors No. 2, No. 4, No. 6 operating sound.
      • Clicking noise should exist. 

    OK or NG 

    • OK: GO TO 12.
    • NG: Perform trouble diagnosis for INJECTOR CIRCUIT, refer to INJECTOR CIRCUIT .
    Fig 9: Listening For Injector Operating Sound
    G02431769Courtesy of NISSAN MOTOR CO., U.S.A.
  12. CHECK INJECTOR 
    1. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
    2. Turn ignition switch OFF.
    3. Disconnect all injector harness connectors.
    4. Remove injector gallery assembly. Refer to FUEL INJECTOR AND FUEL TUBE .

      Keep fuel hose and all injectors connected to injector gallery.

    5. For DTC P0171, reconnect injector harness connectors on bank 1.

      For DTC P0174, reconnect injector harness connectors on bank 2.

    6. Disconnect all ignition coil harness connectors.
    7. Prepare pans or saucers under each injector.
    8. Crank engine for about 3 seconds.

      For DTC P0171, make sure that fuel sprays out from injectors on bank 1.

      For DTC P0174, make sure that fuel sprays out from injectors on bank 2.

      • Fuel should be sprayed evenly for each injector. 
      Fig 10: Checking Injector Spray Pattern
      G02431770Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    • OK: GO TO 13.
    • NG: Replace injectors from which fuel does not spray out.

      Always replace O-ring with new ones.

  13. CHECK INTERMITTENT INCIDENT 

    Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

    • : INSPECTION END 
scientia non olet · About LEMON Manuals