DTC DETECTION LOGIC The heated oxygen sensor 2 has a much longer switching time between rich and lean than the air fuel ratio (A/F) sensor 1. The oxygen storage capacity of the three way catalyst 1 causes the longer switching time. MALFUNCTION A
To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the voltage is unusually high during various driving conditions such as fuelcut.
MALFUNCTION B
To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the minimum voltage of sensor is sufficiently low during various driving conditions such as fuelcut.

DTC No. | Trouble diagnosis name | DTC detecting condition | Possible cause
P0138 | Heated oxygen sensor 2 (bank 1) circuit high voltage | A) | An excessively high voltage from the sensor is sent to ECM. |

- Harness or connectors
  (The sensor circuit is open or shorted)
- Heated oxygen sensor 2

B) | The minimum voltage from the sensor does not reach to the specified voltage. |

- Harness or connectors
  (The sensor circuit is open or shorted)
- Heated oxygen sensor 2
- Fuel pressure
- Fuel injector

P0158 | Heated oxygen sensor 2 (bank 2) circuit high voltage | A) | An excessively high voltage from the sensor is sent to ECM. |

- Harness or connectors
  (The sensor circuit is open or shorted)
- Heated oxygen sensor 2

B) | The minimum voltage from the sensor does not reach to the specified voltage. |

- Harness or connectors
  (The sensor circuit is open or shorted)
- Heated oxygen sensor 2
- Fuel pressure
- Fuel injector

DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test.

1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.

>>GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION A

1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
6. Let engine idle for 2 minutes.
7. Check 1st trip DTC.

Is 1st trip DTC detected?
YES>>Go to Diagnosis Procedure (GT-R certified NISSAN dealer).
NO-1>>With CONSULT-III: GO TO 3.
NO-2>>Without CONSULT-III: GO TO 5.
3.PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION B
NOTE：
For better results, perform “DTC WORK SUPPORT” at a temperature of 0 to 30 °C (32 to 86 °F).

1. Select “DATA MONITOR” mode with CONSULT-III.
2. Start engine and warm it up to the normal operating temperature.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Turn ignition switch ON.
5. Turn ignition switch OFF and wait at least 10 seconds.
6. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
7. Let engine idle for 1 minute.
8. Check that “COOLAN TEMP/S” indicates more than 70°C (158°F).If not, warm up engine and go to next step when “COOLAN TEMP/S” indication reaches 70°C (158°F).
9. Open engine hood.
10. Select “HO2S2 (B1) P1146” (for DTC P0138) or “HO2S2 (B2) P1166” (for DTC P0158) of “HO2S2” in “DTC WORK SUPPORT” mode with CONSULT-III.
11. Follow the instruction of CONSULT-III display.
    NOTE：
    It will take at most 10 minutes until “COMPLETED” is displayed.
12. Touch “SELF-DIAG RESULTS”.

Which is displayed on CONSULT-III screen?
OK>>INSPECTION END
NG>>Go to Diagnosis Procedure (GT-R certified NISSAN dealer).
CON NOT BE DIAGNOSED>>GO TO 4.
4.PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION B AGAIN

1. Turn ignition switch OFF and leave the vehicle in a cool place (soak the vehicle).
2. Perform DTC confirmation procedure again.

>> GO TO 3.
5.PERFORM COMPONENT FUNCTION CHECK FOR MALFUNCTION B
Perform component function check. Refer to Component Function Check (GT-R certified NISSAN dealer).
NOTE：
Use component function check to check the overall function of the heated oxygen sensor 2 circuit. During this check, a 1st trip DTC might not be confirmed.
Is the inspection result normal?
YES>>INSPECTION END
NO>>Go to Diagnosis Procedure (GT-R certified NISSAN dealer).