Diagnostic Procedure

1. Turn ignition switch OFF.
2. Loosen and retighten two engine ground screws. Refer to "GROUND INSPECTION ".

OK or NG

1. OK : GO TO 2.
2. NG : Repair or replace ground connections.
   Fig 1: Checking Engine Ground Connections

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

Loosen and retighten heated oxygen sensor 1.

Fig 2: Identifying Heated Oxygen Sensor

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

Tightening torque: 40 - 50 N.m (4.1 - 5.1 kg-m, 30 - 37 ft-lb) 

1. : GO TO 3.

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".
4. Run engine for at least 10 minutes at idle speed.

   Is the 1st trip DTC P0172 detected? 

   Is it difficult to start engine? 

   Fig 3: CONSULT-II Diagnosis Function Display

   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 5 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 P0172 detected? 

   Is it difficult to start engine? 

   Fig 4: Identifying Mass Air Flow Sensor And Air Cleaner

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

Yes or No

1. Yes : Perform trouble diagnosis for DTC P0172. Refer to DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION .
2. No : GO TO 4.

1. Turn ignition switch OFF.
2. Disconnect heated oxygen sensor 1 harness connector.

   Bank 1 

   Fig 5: Disconnecting Heated Oxygen Sensor 1 Harness Connector (Bank 1)

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

   Bank 2 

   Fig 6: Disconnecting Heated Oxygen Sensor 1 Harness Connector (Bank 2)

   Courtesy of NISSAN MOTOR CO., U.S.A.
3. Check connectors for water.

   Water should not exist. 

OK or NG

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

Refer to "COMPONENT INSPECTION ".

OK or NG

1. OK : GO TO 6.
2. NG : Replace malfunctioning heated oxygen sensor 1.

Refer to "COMPONENT INSPECTION ".

OK or NG

1. OK : GO TO 7.
2. NG : Replace malfunctioning heated oxygen sensor 1.

Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT " For circuit, refer to "WIRING DIAGRAM ".

1. : INSPECTION END