Engine-CodesNissan – P0138 2011 Nissan Sentra

P0138 2011 Nissan Sentra Code - HO2S12 Circuit High Voltage

Quick Answer

The diagnostic trouble code P0138 for a 2011 Nissan Sentra relates to the HO2S12 (Heated Oxygen Sensor Bank 1 Sensor 2) circuit experiencing high voltage. Common causes include Faulty HO2S12 sensor: The sensor may be damaged or worn out, leading to incorrect voltage readings, Wiring issues: Short circuits, open circuits, or damaged wiring can disrupt the signal from the sensor to the ECM, Exhaust leaks: Leaks in the exhaust system can affect the oxygen sensor readings. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means
P0138 2011 Nissan Sentra indicates HO2S12 Circuit High Voltage.
Common causes
Common causes include Faulty HO2S12 sensor: The sensor may be damaged or worn out, leading to incorrect voltage readings, Wiring issues: Short circuits, open circuits, or damaged wiring can disrupt the signal from the sensor to the ECM, Exhaust leaks: Leaks in the exhaust system can affect the oxygen sensor readings.
Severity
Moderate - service should be scheduled soon.
Can I drive?
The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
Table of contents Created and updated by William Orellana on Sep 09, 2024
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Code P0138 2011 Nissan Sentra Description

The diagnostic trouble code P0138 for a 2011 Nissan Sentra relates to the HO2S12 (Heated Oxygen Sensor Bank 1 Sensor 2) circuit experiencing high voltage. This code indicates that the oxygen sensor in the downstream position on the same side as the number one cylinder is sending a signal to the engine control module (ECM) that is higher than the specified voltage range. The HO2S plays a crucial role in monitoring the oxygen levels in the exhaust gases and providing feedback to the ECM for proper air-fuel mixture control.

OBDII Code P0138 2011 Nissan Sentra - HO2S12 Circuit High Voltage
P0138 2011 Nissan Sentra Code - HO2S12 Circuit High Voltage

Common Causes of P0138 2011 Nissan Sentra

  1. Faulty HO2S12 sensor: The sensor may be damaged or worn out, leading to incorrect voltage readings.
  2. Wiring issues: Short circuits, open circuits, or damaged wiring can disrupt the signal from the sensor to the ECM.
  3. Exhaust leaks: Leaks in the exhaust system can affect the oxygen sensor readings.
  4. ECM malfunction: A malfunctioning ECM can also cause high voltage readings from the oxygen sensor.

Symptoms of P0138 2011 Nissan Sentra

  1. Decreased fuel efficiency: The ECM may not be able to adjust the air-fuel mixture correctly, resulting in reduced fuel economy.
  2. Rough idling: Incorrect air-fuel mixture can cause the engine to run unevenly at idle.
  3. Engine hesitation: The engine may hesitate or stumble during acceleration due to the incorrect fuel mixture.
  4. Illuminated check engine light: The P0138 code will trigger the check engine light to illuminate on the dashboard.

How to Fix P0138 2011 Nissan Sentra

  1. Diagnose the issue: Use a scan tool to read the code and pinpoint the exact cause of the high voltage reading.
  2. Test the HO2S12 sensor: Check the sensor's voltage output and resistance to determine if it is functioning correctly.
  3. Inspect wiring: Check the wiring harness for any damage, shorts, or open circuits and repair as necessary.
  4. Replace the HO2S12 sensor: If the sensor is faulty, replace it with a new one and ensure proper installation.
  5. Clear the code: After making the necessary repairs, clear the diagnostic trouble code from the ECM memory to reset the check engine light.

Cost to Fix P0138 2011 Nissan Sentra

The cost of repairing a P0138 code on a 2011 Nissan Sentra can vary depending on the specific cause of the issue. Typically, the cost of a new HO2S12 sensor ranges from $50 to $200, depending on the brand and quality. Labor costs for sensor replacement and diagnostic testing can range from $100 to $300, depending on the shop's hourly rates and the complexity of the repair. Overall, the total repair cost for addressing a P0138 code could range from $150 to $500. It's essential to consult with a qualified mechanic or auto repair shop to get an accurate estimate based on the vehicle's specific condition and location.

Tech Notes for P0138 2011 Nissan Sentra

Replacing the Rear Heated Oxygen Sensor Bank 1 usually takes care of the problem.

When is the Code Detected?

The P0138 code is set when the Engine Control Module (ECM) detects that the rear O2 sensor signal voltage remains excessively high for an extended period of time.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0138 2011 Nissan Sentra Code

1. What does the OBDII code P0138 for a 2011 Nissan Sentra indicate?

The code P0138 on a 2011 Nissan Sentra refers to a fault with the HO2S12 (Heated Oxygen Sensor Bank 1 Sensor 2) circuit showing high voltage.

2. What are the common symptoms of OBDII code P0138 on a 2011 Nissan Sentra?

Common symptoms of code P0138 on a 2011 Nissan Sentra include poor fuel economy, rough idling, stalling, and the illumination of the check engine light.

3. What are the potential causes of the HO2S12 circuit high voltage error on a 2011 Nissan Sentra?

Potential causes of the P0138 code on a 2011 Nissan Sentra can include a faulty oxygen sensor, wiring issues, a vacuum leak, or a problem with the engine's fuel system.

4. How can I diagnose the HO2S12 circuit high voltage issue on my 2011 Nissan Sentra?

To diagnose the P0138 code on a 2011 Nissan Sentra, you can use an OBDII scanner to read the code, visually inspect the wiring and connectors, test the oxygen sensor's voltage, and check for any vacuum leaks.

5. Can a dirty or contaminated oxygen sensor cause the P0138 code on a 2011 Nissan Sentra?

Yes, a dirty or contaminated oxygen sensor can potentially cause the P0138 code on a 2011 Nissan Sentra as it may not function properly and lead to erroneous high voltage readings.

6. What are some repair tips for fixing the HO2S12 circuit high voltage error on a 2011 Nissan Sentra?

Repair tips for addressing the P0138 code on a 2011 Nissan Sentra include cleaning or replacing the oxygen sensor, repairing any damaged wiring, fixing vacuum leaks, and ensuring proper fuel system operation.

7. Is it safe to continue driving my 2011 Nissan Sentra with the P0138 code illuminated?

It is not recommended to continue driving your 2011 Nissan Sentra with the P0138 code illuminated as it can lead to decreased fuel efficiency and potential engine performance issues.

8. Can I reset the check engine light after fixing the HO2S12 circuit high voltage problem on my 2011 Nissan Sentra?

Yes, after addressing the underlying cause of the P0138 code on your 2011 Nissan Sentra, you can reset the check engine light using an OBDII scanner to clear the stored error code.

9. How much does it typically cost to repair the P0138 code on a 2011 Nissan Sentra at a mechanic or dealership?

The cost of repairing the P0138 code on a 2011 Nissan Sentra can vary depending on the exact cause of the issue, but it may range from $100 to $300 for parts and labor at a mechanic or dealership.

10. Are there any recalls or technical service bulletins related to the OBDII code P0138 on a 2011 Nissan Sentra?

Check with your local Nissan dealership or visit the National Highway Traffic Safety Administration (NHTSA) website to see if there are any recalls or technical service bulletins related to the P0138 code on a 2011 Nissan Sentra.

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