Diagnostic Procedure

1. Turn ignition switch OFF.
2. Loosen and retighten engine two screws on the body.

   Refer to "GROUND INSPECTION ".

   Fig 1: Locating ECM Ground Screws On Body

   Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG 

1. OK : GO TO 2.
2. NG : Repair or replace ground connections.

Loosen and retighten the air fuel ratio (A/F) sensor 1.

Fig 2: Locating Air Fuel Ratio (A/F) Sensor 1

Courtesy of NISSAN MOTOR CO., U.S.A.

1. Tightening torque: 40 - 60 N-m (4.1 - 6.1 kg-m, 30 - 44 ft-lb) 
2. : GO TO 3.

1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before three way catalyst (manifold).
   Fig 3: Checking Exhaust Gas Leakage

   Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG 

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

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

OK or NG 

1. OK : GO TO 5.
2. NG : Repair or replace.

With CONSULT-II 

1. Start engine and warm it up to normal operating temperature.
2. Select "SELF-LEARNING CONT" in "WORK SUPPORT" mode with CONSULT-II.
   Fig 4: WORK SUPPORT, SELF-LEARNING CONT - CONSULT-II Display Screen

   Courtesy of NISSAN MOTOR CO., U.S.A.
3. Clear the self-learning control coefficient by touching "CLEAR" or "START".
4. Run engine for at least 10 minutes at idle speed.

   Is the 1st trip DTC P0171 or P0172 detected? Is it difficult to start engine? 

Without CONSULT-II 

1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF.
3. Disconnect mass air flow sensor harness connector, and restart and run engine for at least 5 seconds at idle speed.
   Fig 5: Identifying Mass Air Flow Sensor

   Courtesy of NISSAN MOTOR CO., U.S.A.
4. Stop engine and reconnect mass air flow sensor harness connector.
5. Make sure DTC P0102 is displayed.
6. Erase the DTC memory. Refer to "HOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION ".
7. Make sure DTC P0000 is displayed.
8. Run engine for at least 10 minutes at idle speed.

   Is the 1st trip DTC P0171 or P0172 detected? Is it difficult to start engine? 

Yes or No 

1. Yes : Perform trouble diagnosis for DTC P0171, P0172. Refer to DTC P0171 FUEL INJECTION SYSTEM FUNCTION , DTC P0172 FUEL INJECTION SYSTEM FUNCTION .
2. No : GO TO 6.

1. Turn ignition switch OFF.
2. Disconnect A/F sensor 1 harness connector.
   Fig 6: Disconnecting A/F Sensor 1 Harness Connector

   Courtesy of NISSAN MOTOR CO., U.S.A.
3. Turn ignition switch ON.
4. Check voltage between A/F sensor 1 terminal 3 and ground with CONSULT-II or tester.
   1. Voltage: Battery voltage 

Fig 7: Checking Voltage Between A/F Sensor 1 Connector Terminal 3 And Ground

Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG 

1. OK : GO TO  8.
2. NG : GO TO 7.

Check the following.

• Harness connectors M19, E108
• Harness connectors E10, F48
• Fuse block (J/B) connector M1
• 15 fuse
• Harness for open or short between A/F sensor 1 and fuse
  1. : Repair or replace harness or connectors.

1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between the following terminals. Refer to WIRING DIAGRAM .
   ECM TERMINALS AND A/F SENSOR 1 TERMINALS REFERENCE
   
   

   A/F sensor 1 terminal	ECM terminal
   1	16
   5	35
   6	56
   2	75

   1. Continuity should exist. 
4. Check harness continuity between ECM terminals 16, 35, 56, 75 or A/F sensor 1 terminals 1, 2, 5, 6 and ground. Refer to WIRING DIAGRAM .
   1. Continuity should not exist. 
5. Also check harness for short to power.

OK or NG 

1. OK : GO TO 9.
2. NG : Repair open circuit or short to ground or short to power in harness or connectors.

Refer to "COMPONENT INSPECTION ".

OK or NG 

1. OK : GO TO 10.
2. NG : Replace A/F sensor 1.

Refer to "COMPONENT INSPECTION ".

OK or NG 

1. OK : GO TO 11.
2. NG : Replace mass air flow sensor.

Refer to "COMPONENT INSPECTION ".

OK or NG 

1. OK : GO TO 12.
2. NG : Repair or replace PCV valve.

Perform "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

OK or NG 

1. OK : Replace A/F sensor 1.
2. NG : Repair or replace.