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.
3. Disconnect corresponding heated oxygen sensor 1 harness connector.
   Fig 2: Disconnecting Corresponding Heated Oxygen Sensor 1 Harness Connector

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

   Refer to WIRING DIAGRAM  .

   Continuity should exist. 

5. Also check harness for short to power.

OK or NG 

1. OK GO TO 2.
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 3: 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 4: 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 (With CONSULT-II) GO TO 3.
2. OK (Without CONSULT-II) GO TO  4 .
3. NG Repair open circuit or short to ground or short to power in harness or connectors.

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 5: 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 6: Identifying Heated Oxygen Sensor Voltage Signal

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

OK or NG 

1. OK GO TO  5 .
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 7: 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 5.
2. NG Replace malfunctioning heated oxygen sensor 1.

Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT  " .

1. INSPECTION END