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Engine-Codes – Nissan – P0138 2012 Nissan Sentra

P0138 2012 Nissan Sentra Code - HO2S12 Circuit High Voltage

Quick Answer

The P0138 code for a 2012 Nissan Sentra indicates an issue with the HO2S12 (Heated Oxygen Sensor 1 Bank 1 Sensor 2) circuit registering high voltage. Common causes include Faulty HO2S12 sensor, Damaged wiring or connectors in the sensor circuit, ECM issues. 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 2012 Nissan Sentra indicates HO2S12 Circuit High Voltage.
Common causes
Common causes include Faulty HO2S12 sensor, Damaged wiring or connectors in the sensor circuit, ECM issues.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 09, 2024
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Code P0138 2012 Nissan Sentra Description

The P0138 code for a 2012 Nissan Sentra indicates an issue with the HO2S12 (Heated Oxygen Sensor 1 Bank 1 Sensor 2) circuit registering high voltage. The HO2S12 sensor is responsible for monitoring the oxygen levels in the exhaust gases and sending this information to the engine control module (ECM) to adjust the air-fuel mixture for optimal combustion. When the voltage from the sensor is higher than expected, it can lead to a variety of performance issues in the vehicle.

OBDII Code P0138 2012 Nissan Sentra - HO2S12 Circuit High Voltage
P0138 2012 Nissan Sentra Code - HO2S12 Circuit High Voltage

Common Causes of P0138 2012 Nissan Sentra

  1. Faulty HO2S12 sensor.
  2. Damaged wiring or connectors in the sensor circuit.
  3. ECM issues.
  4. Exhaust leaks near the sensor.
  5. Engine running rich due to other problems.

Symptoms of P0138 2012 Nissan Sentra

  1. Check engine light illuminated on the dashboard.
  2. Decreased fuel efficiency.
  3. Rough idling or engine misfires.
  4. Lack of power during acceleration.
  5. Increased emissions output.

How to Fix P0138 2012 Nissan Sentra

  1. Begin by diagnosing the issue using a scan tool to confirm the P0138 code and pinpoint the exact cause.
  2. Inspect the wiring and connectors for any damage or corrosion. Repair or replace as needed.
  3. Test the HO2S12 sensor using a multimeter to check for proper voltage output.
  4. If the sensor is faulty, replace it with a new one and clear the code from the ECM.
  5. After repairs are made, perform a test drive to ensure the issue is resolved and the check engine light does not reappear.

Cost to Fix P0138 2012 Nissan Sentra

The cost estimate for repairing a P0138 code on a 2012 Nissan Sentra can vary depending on the exact cause of the issue. On average, replacing a faulty oxygen sensor can cost between $200 and $300, including parts and labor. If wiring repairs or ECM diagnosis are needed, the total cost could be higher. It's recommended to consult with a trusted mechanic or dealership for a more accurate estimate based on the specific situation. Keep in mind that labor rates can vary between auto repair shops, so it's advisable to shop around for the best price.

What does this mean?

Tech Notes for P0138 2012 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 2012 Nissan Sentra Code

1. What does OBDII code P0138 on a 2012 Nissan Sentra mean?

The OBDII code P0138 for a 2012 Nissan Sentra indicates a fault with the HO2S12 (Heated Oxygen Sensor Bank 1 Sensor 2) circuit, specifically high voltage.

2. What are the common symptoms of OBDII code P0138 on a 2012 Nissan Sentra?

Common symptoms of OBDII code P0138 on a 2012 Nissan Sentra may include poor fuel economy, rough idling, engine hesitation, or the illumination of the check engine light.

3. What are the possible causes of OBDII code P0138 on a 2012 Nissan Sentra?

Possible causes of OBDII code P0138 on a 2012 Nissan Sentra include a faulty HO2S12 sensor, wiring issues in the sensor circuit, exhaust leaks, or a malfunctioning engine control module (ECM).

4. How can I diagnose the HO2S12 circuit high voltage issue in a 2012 Nissan Sentra?

To diagnose the HO2S12 circuit high voltage issue in a 2012 Nissan Sentra, you can use a scan tool to read the code, visually inspect the sensor and its wiring for any damage, and perform voltage tests to determine if the sensor is functioning correctly.

5. Is it safe to continue driving a 2012 Nissan Sentra with OBDII code P0138?

It is not recommended to continue driving a 2012 Nissan Sentra with OBDII code P0138, as it can lead to decreased fuel efficiency and potential damage to the catalytic converter.

6. Can I repair OBDII code P0138 on a 2012 Nissan Sentra myself?

Depending on your mechanical skills, you may be able to repair OBDII code P0138 on a 2012 Nissan Sentra yourself by replacing the faulty HO2S12 sensor, fixing any wiring issues, or addressing exhaust leaks. However, professional diagnosis and repair may be necessary for complex cases.

7. How much does it cost to fix OBDII code P0138 on a 2012 Nissan Sentra?

The cost to fix OBDII code P0138 on a 2012 Nissan Sentra can vary depending on the underlying issue. Replacing a faulty HO2S12 sensor may range from $100 to $300, while addressing wiring or ECM problems can increase the repair cost.

8. Can a bad HO2S12 sensor cause other issues in a 2012 Nissan Sentra?

Yes, a bad HO2S12 sensor can cause other issues in a 2012 Nissan Sentra, such as poor engine performance, increased emissions, and potential damage to the catalytic converter if left unresolved.

9. How often should the HO2S12 sensor be replaced in a 2012 Nissan Sentra?

The HO2S12 sensor in a 2012 Nissan Sentra typically lasts around 100,000 miles, but it is recommended to follow the manufacturer's maintenance schedule and replace it if any issues or codes like P0138 arise.

10. Is OBDII code P0138 a common issue in 2012 Nissan Sentras?

OBDII code P0138, indicating HO2S12 circuit high voltage, is a relatively common issue in 2012 Nissan Sentras, especially as the vehicle ages and the sensor or related components wear out. Regular maintenance and timely repairs can help prevent this code from recurring.

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