Diagnostic Procedure

1. Turn ignition switch OFF.
2. Loosen and retighten engine ground screws. See Figure .

1. : GO TO 2.

Loosen and retighten corresponding heated oxygen sensor 1.

Tightening torque: 

40 - 60 N.m (4.1 - 6.1 Kg-m, 30 - 44 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. See Figure .
4. Run engine for at least 10 minutes at idle speed.

   Is the 1st trip DTC P0171 or P0174 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.
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 P0174 detected? 

   Is it difficult to start engine? 

YES or NO 

1. YES: Perform trouble diagnosis for DTC P0171, P0174. Refer to DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION 
2. NO: GO TO 4.

1. Stop engine.
2. Disconnect HO2S1 harness connector.
3. Check resistance between HO2S1 terminals as follows.
   Fig 1: Checking Heated Oxygen Sensor 1 Heater

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

OK or NG 

1. OK (With CONSULT-II): GO TO 5.
2. OK (Without CONSULT-II): GO TO  6 .
3. NG: Replace malfunctioning heated oxygen sensor 1.

With CONSULT-II 

1. Start engine and warm it up to normal operating temperature.
2. Select MANU TRIG and adjust TRIGGER POINT to 100% in DATA MONITOR mode with CONSULT-II.
3. Select HO2S1 (B1)/(B2) and HO2S1 MNTR (B1)/(B2).
4. Hold engine speed at 2,000 rpm under no load during the following steps.
5. Touch RECORD on CONSULT-II screen. See Figure .
6. Check the following.
   • HO2S1 MNTR (B1)/(B2) in DATA MONITOR mode changes from RICH to LEAN to RICH more than 5 times in 10 seconds.

     5 times (cycles) are counted as shown in Figure .

   • HO2S1 (B1)/(B2) voltage goes above 0.6V at least once.
   • HO2S1 (B1)/(B2) voltage goes below 0.3V at least once.
   • HO2S1 (B1)/(B2) voltage never exceeds 1.0V. See Figure .
   CAUTION:

   • Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a hard surface such as a concrete floor; use a new one.
   • Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.

   OK or NG 

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

Without CONSULT-II 

1. Start engine and warm it up to normal operating temperature.
2. Set voltmeter probes between ECM terminal 91 (HO2S1 bank 1 signal) or 92 (HO2S1 bank 2 signal) and engine ground.
3. Check the following with engine speed held at 2,000 rpm constant under no load.

• The voltage fluctuates between 0 to 0.3V and 0.6 to 1.0V more than 5 times within 10 seconds.
• The maximum voltage is over 0.6V at least one time.
• The minimum voltage is below 0.3V at least one time.
• The voltage never exceeds 1.0V.
  1. 1 time 0 - 0.3V --> 0.6 - 1.0V --> 0 - 0.3V
  2. 2 times: 0 - 0.3V --> 0.6 - 1.0V --> 0 - 0.3V --> 0.6 - 1.0V --> 0 - 0.3V

     See Figure .

     CAUTION:

     • Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a hard surface such as a concrete floor; use a new one.
     • Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.

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