Diagnostic Procedure

1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. Refer to "GROUND INSPECTION ".
   Fig 1: Checking Ground Connections

   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.

Tightening torque: 40 - 60 N.m (4.1 - 6.1 kg-m, 30 - 44 ft-lb) 

1. : GO TO 3.

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

   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.
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? 

   Fig 3: Displaying WORK SUPPORT Mode

   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, and restart and run engine for at least 3 seconds at idle speed.
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? 

   Fig 4: Identifying Mass Air Flow Sensor

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

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. Disconnect A/F sensor 1 harness connector.
2. Turn ignition switch ON.
   Fig 5: Disconnecting A/F Sensor 1 Harness Connector

   Courtesy of NISSAN MOTOR CO., U.S.A.
3. Check voltage between A/F sensor 1 terminal 3 and ground with CONSULT-II or tester.

   Voltage: Battery voltage 

OK or NG

1. OK : GO TO  8.
2. NG : GO TO 7.
   Fig 6: Checking Voltage Between A/F Sensor 1 Terminal 3 & Ground

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

Check the following.

• Harness connectors E21, F34
• IPDM E/R harness connector E122
• 10A 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 .
   TERMINALS REFERENCE
   
   

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

   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 .

   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.