Nissan Sentra B18 (2020-2025) Service Manual: P2a01 O2 Sensor 2 Bank 1

Dtc Description

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 (manifold) 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 fuel cut.

MALFUNCTION B

To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the minimum voltage is excessively high during various driving conditions such as fuel cut.

• An excessively high voltage from the sensor is sent to ECM.

• The minimum voltage from the sensor is not reached to the specified voltage.

POSSIBLE CAUSE

P2A01-A

• Harness or connectors (The heated oxygen sensor 2 circuit is open or shorted.)

• Heated oxygen sensor 2

P2A01-B

• Harness or connectors (The heated oxygen sensor 2 circuit is open or shorted.)

• Heated oxygen sensor 2

• Fuel pressure

• Fuel injector

FAIL-SAFE

Not applicable

Confirmation Procedure

1. PRECONDITIONING

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

   >>

   GO TO 2.

2. 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. Restart engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.

   4. Check 1st trip DTC.

   Is 1st trip DTC detected?

   YES >>

   Proceed to DTC Diagnosis Procedure.

   NO-1 >>

   With CONSULT: GO TO 3.

   NO-2 >>

   Without CONSULT: GO TO 5.

3. DTC CONFIRMATION PROCEDURE FOR MALFUNCTION B-1

   WITH CONSULT

   Test condition : For better results, perform “DTC WORK SUPPORT” at a temperature of 0 to 30°C (32 to 86°F).

   1. Turn ignition switch ON and select “DATA MONITOR” mode with CONSULT.

   2. Start engine and warm it up to the normal operating temperature.

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

   4. Restart engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.

   5. Let engine idle for 1 minute.

   6. 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).

   7. Open engine hood.

   8. Select “O2 (B1) P0138” of “HO2S2” in “DTC WORK SUPPORT” mode with CONSULT.

   9. Follow the instruction of CONSULT display.

      Note:

      It will take at most 10 minutes until “COMPLETED”is displayed.

   10. Touch “SELF-DIAG RESULTS”.

   Which is displayed on CONSULT screen?

   OK-1>>

   To check malfunction symptom before repair: Refer to Intermittent Incident.

   OK-2>>

   Confirmation after repair: INSPECTION END

   NG>>

   Proceed to DTC Diagnosis Procedure.

   CAN NOT BE DIAGNOSED>>

   GO TO 4.

4. DTC CONFIRMATION PROCEDURE FOR MALFUNCTION B-2

   1. Turn ignition switch OFF and leave the Nissan Sentra vehicle in a cool place (soak the vehicle).

   2. Perform DTC confirmation procedure again.

   >>

   GO TO 3.

5. PERFORM COMPONENT FUNCTION CHECK-1

   WITHOUT CONSULT

   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.

   1. Start engine and warm it up to the normal operating temperature.

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

   3. Restart engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.

   4. Let engine idle for 1 minute.

   5. Check the voltage between ECM harness connector terminals under the following conditions.

      ECM			Condition	Voltage
      Connector	+	–
      	Terminal
      F25	77	76	Revving up to 4,000 rpm quickly under no load at least 10 times. (Depress and release the accelerator pedal as quickly as possible.)	The voltage should be above 0.73 V at least once during this procedure. The voltage should be below 0.18 V at least once during this procedure.

   Is the inspection result normal?

   YES-1 >>

   To check malfunction symptom before repair: Refer to Intermittent Incident.

   YES-2 >>

   Confirmation after repair: INSPECTION END

   NO >>

   GO TO 6.

6. PERFORM COMPONENT FUNCTION CHECK-2

   WITHOUT CONSULT

   Check the voltage between ECM harness connector terminals under the following conditions.

   ECM			Condition	Voltage
   Connector	+	–
   	Terminal
   F25	77	76	Keeping engine at idle for 10 minutes.	The voltage should be above 0.73 V at least once during this procedure. The voltage should be below 0.18 V at least once during this procedure.

   Is the inspection result normal?

   YES-1 >>

   To check malfunction symptom before repair: Refer to Intermittent Incident.

   YES-2 >>

   Confirmation after repair: INSPECTION END

   NO >>

   GO TO 7.

7. PERFORM COMPONENT FUNCTION CHECK-3

   Check the voltage between ECM harness connector terminals under the following conditions.

   CAUTION:

   Always drive Nissan Sentra vehicle at a safe speed.

   ECM			Condition	Voltage
   Connector	+	–
   	Terminal
   F25	77	76	Coasting from 80 km/h (50 MPH) with selector lever in the D position.	The voltage should be above 0.73 V at least once during this procedure. The voltage should be below 0.18 V at least once during this procedure.

   Is the inspection result normal?

   YES-1 >>

   To check malfunction symptom before repair: Refer to Intermittent Incident.

   YES-2 >>

   Confirmation after repair: INSPECTION END

   NO >>

   Proceed to DTC Diagnosis Procedure.

Dtc Diagnosis Procedure

1. INSPECTION START

   1. Confirm the detected malfunction (A or B). Refer to DTC Description.

   Which malfunction is detected?

   A>>

   GO TO 2.

   B>>

   GO TO 7.

2. CHECK HEATED OXYGEN SENSOR 2 CONNECTOR

   1. Disconnect heated oxygen sensor 2 (HO2S2) harness connector.

   2. Check that water is not inside connectors.

   There is no leakage.

   Is the inspection result normal?

   YES >>

   GO TO 3.

   NO >>

   Repair or replace malfunctioning part.

3. CHECK HO2S2 GROUND CIRCUIT FOR OPEN AND SHORT

   1. Turn ignition switch OFF.

   2. Disconnect ECM harness connector.

   3. Disconnect heated oxygen sensor 2 (HO2S2) harness connector.

   4. Check the continuity between HO2S2 harness connector and ECM harness connector.

      HO2S2		ECM		Continuity
      Connector	Terminal	Connector	Terminal
      E72	1	F25	76	Existed

   5. Also check harness for short to ground and short to power.

   Is the inspection result normal?

   YES >>

   GO TO 4.

   NO >>

   Repair or replace malfunctioning part.

4. CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

   1. Check the continuity between HO2S2 harness connector and ECM harness connector.

      HO2S2		ECM		Continuity
      Connector	Terminal	Connector	Terminal
      E72	2	F25	77	Existed

   2. Check the continuity between HO2S2 harness connector and ground, or ECM harness connector and ground.

      HO2S2		Ground	Continuity
      Connector	Terminal
      E72	2	Ground	Not existed

      ECM		Ground	Continuity
      Connector	Terminal
      F25	77	Ground	Not existed

   3. Also check harness for short to ground and short to power.

   Is the inspection result normal?

   YES >>

   GO TO 5.

   NO >>

   Repair or replace malfunctioning part.

5. CHECK HEATED OXYGEN SENSOR 2

   Refer to Component Inspection.

   Is the inspection result normal?

   YES >>

   INSPECTION END

   NO >>

   GO TO 6.

6. REPLACE HEATED OXYGEN SENSOR 2

   Replace malfunctioning heated oxygen sensor 2. Refer to Exploded View.

   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.

   >>

   INSPECTION END

7. CLEAR THE MIXTURE RATIO SELF-LEARNING VALUE

   1. Start engine and warm it up to the normal operating temperature.

   2. Clear the mixture ratio self-learning value. Refer to Work Procedure.

   3. Run engine for at least 10 minutes at idle speed.

   Is the 1st trip DTC P0172 detected? Is it difficult to start engine?

   YES >>

   Perform trouble diagnosis for DTC P0172. Refer to DTC Diagnosis Procedure.

   NO >>

   GO TO 8.

8. CHECK HEATED OXYGEN SENSOR 2 GROUND CIRCUIT FOR OPEN AND SHORT

   1. Turn ignition switch OFF.

   2. Disconnect ECM harness connector.

   3. Disconnect heated oxygen sensor 2 (HO2S2) harness connector.

   4. Check the continuity between HO2S2 harness connector and ECM harness connector.

      HO2S2		ECM		Continuity
      Connector	Terminal	Connector	Terminal
      E72	1	F25	76	Existed

   5. Also check harness for short to ground and short to power.

   Is the inspection result normal?

   YES >>

   GO TO 9.

   NO >>

   Repair or replace malfunctioning part.

9. CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

   1. Check the continuity between HO2S2 harness connector and ECM harness connector.

      HO2S2		ECM		Continuity
      Connector	Terminal	Connector	Terminal
      E72	2	F25	77	Existed

   2. Check the continuity between HO2S2 harness connector and ground, or ECM harness connector and ground.

      HO2S2		Ground	Continuity
      Connector	Terminal
      E72	2	Ground	Not existed

      ECM		Ground	Continuity
      Connector	Terminal
      F25	77	Ground	Not existed

   3. Also check harness for short to ground and short to power.

   Is the inspection result normal?

   YES >>

   GO TO 10.

   NO >>

   Repair or replace malfunctioning part.

10. CHECK HEATED OXYGEN SENSOR 2

    Refer to Component Inspection.

    Is the inspection result normal?

    YES >>

    INSPECTION END

    NO >>

    GO TO 11.

11. REPLACE HEATED OXYGEN SENSOR 2

    Replace malfunctioning heated oxygen sensor 2. Refer to Exploded View.

    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.

    >>

    INSPECTION END

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