Diagnostic Procedure

CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten ground three screws on the body.
  
  Fig 1: DTC P1146, P1166 HO2S2 Checking Ground Connections
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Refer to GROUND INSPECTION .
OK or NG

OK: GO TO 2.

NG: Repair or replace ground connections.
CLEAR THE SELF-LEARNING DATA
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 or P0175 detected?
  
  Is it difficult to start engine?
  
  Fig 2: Selecting "SELF-LEARNING CONT" In "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, 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 or P0175 detected?
  
  Is it difficult to start engine?
Yes or No

Yes: Perform trouble diagnosis for DTC P0172, P0175. Refer to DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION .

No: GO TO 3.

Fig 3: Locating Mass Air Flow Sensor (With Intake Air Temperature Sensor)
Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK HO2S2 GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect heated oxygen sensor 2 harness connector.
  
  Fig 4: Locating Heated Oxygen Sensor 2 Harness Connector
  Courtesy of NISSAN MOTOR CO., U.S.A.
3. Check harness continuity between HO2S2 terminal 4 and body ground. Refer to Wiring Diagram.
  Continuity should exist.
4. Also check harness for short to power.
OK or NG

OK: GO TO 5.

NG: GO TO 4.
DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors F14, E5
- Harness for open or short between HO2S2 and body ground
  : Repair open circuit or short to power in harness or connectors.
CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal and HO2S2 terminal as follows. Refer to Wiring Diagram.
  
  Fig 5: DTC P1146, P1166 HO2S2 Checking Harness Continuity Between ECM Terminal & HO2S2 terminal
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Continuity should exist.
3. Check harness continuity between the following terminals and ground. Refer to Wiring Diagram.
  
  Fig 6: DTC P1146, P1166 HO2S2 Checking Harness Continuity Between ECM Terminals & Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Continuity should not exist.
4. Also check harness for short to ground or short to power.
OK or NG

OK: GO TO 6.

NG: Repair open circuit or short to ground or short to power in harness or connectors.
CHECK HEATED OXYGEN SENSOR 2
Refer to COMPONENT INSPECTION .

OK or NG

OK: GO TO 7.

NG: Replace malfunctioning heated oxygen sensor 2.
CHECK INTERMITTENT INCIDENT
Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

: INSPECTION END