Diagnostic Procedure

1. Turn ignition switch "OFF".
2. Loosen and retighten engine ground screws.
   Fig 1: Retightening Engine Ground Screws

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

1. GO TO 2.

Loosen and retighten corresponding heated oxygen sensor 1.

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 For 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".
   Fig 3: Display CONSULT II (Work Support)

   Courtesy of NISSAN MOTOR CO., U.S.A.
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. 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, 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  , 278.
2. No GO TO 6.

1. Turn ignition switch "OFF".
2. Disconnect corresponding heated oxygen sensor 1 harness connector.
   Fig 4: Disconnecting Corresponding Heated Oxygen Sensor 1 Harness Connector

   Courtesy of NISSAN MOTOR CO., U.S.A.
3. Check harness continuity between HO2S1 terminal 4 and engine ground.

   Refer to WIRING DIAGRAM  .

   Continuity should exist. 

4. Also check harness for short to power.

OK or NG 

1. OK GO TO 7.
2. NG Repair open circuit or short to power in harness or connectors.

1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal and HO2S1 terminal as follows.

   Refer to WIRING DIAGRAM  .

   Fig 5: ECM Terminal And HO2S1 Terminals Table (For Continuity Checking)

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

   Continuity should exist. 

3. Check harness continuity between ECM terminal or HO2S1 terminal and ground as follows.

   Refer to WIRING DIAGRAM  .

   Fig 6: ECM Terminal Or HO2S1 Terminal And Ground Table (For Continuity Checking)

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

   Continuity should not exist. 

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 7: Checking Resistance Between HO2S1 Terminals

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

OK or NG 

1. OK GO TO 9.
2. NG GO TO  13 .

1. Reconnect harness connectors disconnected.
2. Start engine and warm it up to normal operating temperature.
3. Check voltage between ECM terminal 51 (Mass air flow sensor signal) and ground.
   Fig 8: Checking Voltage Between ECM Terminal 51 (Mass Air Flow Sensor Signal) And 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 ventilation hose from PCV valve.
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 9: 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 "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.
   Fig 10: Display CONSULT II (Data Monitor)

   Courtesy of NISSAN MOTOR CO., U.S.A.
6. Check the following.

• "HO2S1 MNTR (B1)/(B2)" in "DATA MONITOR" mode changes from "RICH" to "LEAN" to "RICH" 5 times in 10 seconds. 5 times (cycles) are counted as shown below.

  Bank 1

  cycle | 1 | 2 | 3 | 4 | 5 |

  HO2S1 MNTR (B1) R-L-R-L-R-L-R-L-R-L-R

  Bank 2

  cycle | 1 | 2 | 3 | 4 | 5 |

  HO2S1 MNTR (B2) R-L-R-L-R-L-R-L-R-L-R

  R means HO2S1

  MNTR (B1)/(B2) indicates RICH

  L means HO2S1

  MNTR (B1)/(B2) indicates LEAN

• "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.
  Fig 11: Identifying Heated Oxygen Sensor Voltage Signals

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

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 35 (HO2S1 bank 1 signal) or 16 (HO2S1 bank 2 signal) and engine ground.
3. Check the following with engine speed held at 2,000 RPM constant under no load.
   Fig 12: Checking Voltage Between ECM Terminal 35 (HO2S1 Bank 1 Signal) Or 16 (HO2S1 Bank 2 Signal) And Engine Ground

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

• 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 time: 0 - 0.3V --> 0.6 - 1.0V --> 0 - 0.3V

  2 times: 0 - 0.3V --> 0.6 - 1.0V --> 0 - 0.3V --> 0.6 - 1.0V --> 0 - 0.3V

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