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.

1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before three way catalyst (manifold).
   Fig 1: Identifying 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. See Figure .
4. 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? 

Without CONSULT-II

1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF.
3. Turn ignition switch OFF.
4. Disconnect mass air flow sensor harness connector, and restart and run engine for at least 5 seconds at idle speed.
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? 

   Yes or NO 

1. Yes: Perform trouble diagnosis for DTC P0171, P0174 or P0172, P0175. Refer to DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION  , DTC P0172, P0175 FUEL INFECTION SYSTEM FUNCTION  .
2. No: GO TO 6.

1. Turn ignition switch OFF.
2. Disconnect corresponding heated oxygen sensor 1 harness connector. See Figure and Figure .

1. : GO TO 7.

1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal and HO2S1 terminal as follows. Refer to Wiring Diagram.
   Fig 2: Checking ECM & HO2S1 Terminal Continuity

   Courtesy of NISSAN MOTOR CO., U.S.A.
3. Check harness continuity between ECM terminal or HO2S1 terminal and ground as follows. Refer to Wiring Diagram.
   Fig 3: Checking ECM Or HO2S1 Terminal & Ground Continuity

   Courtesy of NISSAN MOTOR CO., U.S.A.
4. Also check harness for short to power.

   OK or NG 

1. OK: GO TO 8.
2. NG: Repair open circuit or short to ground or short to power in harness or connectors.

Check resistance between HO2S1 terminals as follows.

Fig 4: Checking Resistance Between Terminals

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

OK or NG 

1. OK: GO TO 9.
2. NG: Replace malfunctioning heated oxygen sensor 1.

1. Reconnect harness connectors disconnected.
2. Start engine and warm it up to normal operating temperature.
3. Check voltage between ECM terminal 62 (Mass air flow sensor signal) and ground.
   Fig 5: Checking Voltage Between Terminal & Ground

   Courtesy of NISSAN MOTOR CO., U.S.A.
4. If the voltage is out of specification, disconnect mass air flow sensor harness connector and connect it again. Then repeat above check.

   OK or NG 

1. OK: GO TO 10.
2. NG: Replace mass air flow sensor.

1. Install all removed parts.
2. Start engine and let it idle.
3. Remove PCV valve from rocker cover.
4. Make sure that a hissing noise will be heard as air passes through it and a strong vacuum should be felt immediately when a finger is placed over valve inlet.
   Fig 6: Checking PCV Valve

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

   OK or NG 

1. OK (With CONSULT-II): GO TO 11.
2. OK (Without CONSULT-II): GO TO  12 .
3. NG: Replace PCV valve.

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 MANU TRIG 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  13 .
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.
   Fig 7: Checking Voltage Of Heated Oxygen Sensor 1

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

   • Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (1907 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 13.
2. NG: Replace malfunctioning heated oxygen sensor 1.

Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT  .

1. : INSPECTION END