Diagnostic Procedure

1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. Refer to "GROUND INSPECTION ".
   Fig 1: Loosen & Retighten Three Ground Screws On The Body

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

OK or NG

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

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

Fig 2: Loosen & Retighten The Air Fuel Ratio (A/F) Sensor 1

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

• Tightening torque: 50 N.m (5.1 kg.m, 37 ft.lb) 
• : GO TO 3.

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

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

OK or NG

• OK: GO TO 4.
• NG: Repair or replace.

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

OK or NG

• OK: GO TO 5.
• 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.
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, P172, P0174 or P0175 detected? 

   Is it difficult to start engine? 

   Fig 4: Scan Tool Display "Work Support"

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

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.
4. Restart engine and let it idle for at least 5 seconds.
5. Stop engine and reconnect mass air flow sensor harness connector.
6. Make sure DTC P0102 is displayed.
7. Erase the DTC memory. Refer to "HOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION ".
8. Make sure DTC P0000 is displayed.
9. Run engine for at least 10 minutes at idle speed.

   Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected? 

   Is it difficult to start engine? 

   Fig 5: Mass Air Flow Sensor

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

Yes or No

• Yes: Perform trouble diagnosis for DTC P0171, P0174 or P0172, P0175. Refer to DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION  or DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION .
• 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.
   • Voltage: Battery voltage 

OK or NG

• OK: GO TO  8.
• NG: GO TO 7.

Fig 7: A/F Sensor 1 Terminal 3 & Ground Voltage Test

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

Check the following.

• Harness connectors M15, E108
• Harness connectors E12, F3
• Fuse block (J/B) connector M4
• 15A fuse
• Harness for open or short between A/F sensor 1 and fuse
  • : 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 .
   Fig 8: A/F Sensor 1 Terminal & ECM Terminal Specification Table

   Courtesy of NISSAN MOTOR CO., U.S.A.
   • Continuity should exist. 
4. Check harness continuity between the following terminals and ground. Refer to WIRING DIAGRAM .
   Fig 9: A/F Sensor 1 Terminal & ECM Terminal BANK 1 & 2 Specification Table

   Courtesy of NISSAN MOTOR CO., U.S.A.
   • Continuity should not exist. 
5. Also check harness for short to power and short to ground.

OK or NG

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

Refer to "COMPONENT INSPECTION ".

OK or NG

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

Refer to "COMPONENT INSPECTION ".

OK or NG

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

Refer to "POSITIVE CRANKCASE VENTILATION ".

OK or NG

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

Perform "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

OK or NG

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