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P0138 2012 Nissan Altima Sedan Code - HO2S12 Circuit High Voltage

Quick Answer

The P0138 diagnostic trouble code (DTC) for a 2012 Nissan Altima Sedan indicates an issue with the HO2S12 sensor circuit, specifically reporting high voltage. Common causes include Faulty HO2S12 sensor, Damaged wiring or connectors in the sensor circuit, Vacuum leaks in the intake system. 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 Altima Sedan indicates HO2S12 Circuit High Voltage.
Common causes
Common causes include Faulty HO2S12 sensor, Damaged wiring or connectors in the sensor circuit, Vacuum leaks in the intake system.
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 17, 2024
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Code P0138 2012 Nissan Altima Sedan Description

The P0138 diagnostic trouble code (DTC) for a 2012 Nissan Altima Sedan indicates an issue with the HO2S12 sensor circuit, specifically reporting high voltage. The HO2S12 sensor is part of the vehicle's oxygen sensor system, which monitors the oxygen levels in the exhaust gases to ensure optimal fuel efficiency and emissions. When the HO2S12 sensor detects a high voltage signal, it means that the oxygen levels in the exhaust are not within the expected range, which can lead to poor engine performance, decreased fuel efficiency, and increased emissions.

OBDII Code P0138 2012 Nissan Altima Sedan - HO2S12 Circuit High Voltage
P0138 2012 Nissan Altima Sedan Code - HO2S12 Circuit High Voltage

Common Causes of P0138 2012 Nissan Altima Sedan

  1. Faulty HO2S12 sensor
  2. Damaged wiring or connectors in the sensor circuit
  3. Vacuum leaks in the intake system
  4. Engine running rich or lean
  5. Exhaust system leaks

Symptoms of P0138 2012 Nissan Altima Sedan

  1. Check engine light illuminated
  2. Decreased fuel efficiency
  3. Rough idling or stalling
  4. Engine misfires
  5. Increased emissions

How to Fix P0138 2012 Nissan Altima Sedan

  1. Use an OBD-II scanner to confirm the P0138 code and identify the specific issue.
  2. Inspect the HO2S12 sensor, wiring, and connectors for any signs of damage or corrosion.
  3. Test the sensor's voltage output to determine if it is within the manufacturer's specifications.
  4. Replace the HO2S12 sensor if it is faulty, ensuring proper installation and connection.
  5. Clear the DTC and test drive the vehicle to verify that the issue has been resolved.

Cost to Fix P0138 2012 Nissan Altima Sedan

The typical repair costs for addressing a P0138 code on a 2012 Nissan Altima Sedan can range from $150 to $300, including parts and labor. However, the specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. It is advisable to check local rates for a more precise estimate. Keep in mind that rates in metropolitan areas or at dealerships may be higher, while independent shops often charge less.

What does this mean?

Tech Notes for P0138 2012 Nissan Altima Sedan

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 Altima Sedan Code

1. What does the OBDII code P0138 for a 2012 Nissan Altima Sedan mean?

This code indicates that the HO2S12 (Heated Oxygen Sensor 2, Bank 1 Sensor 2) circuit is registering a high voltage condition.

2. What are the common symptoms of OBDII code P0138 in a 2012 Nissan Altima Sedan?

Common symptoms include poor fuel economy, rough idling, engine hesitation, and an illuminated check engine light on the dashboard.

3. What are the possible causes of the HO2S12 circuit high voltage code in a 2012 Nissan Altima Sedan?

Potential causes include a faulty oxygen sensor, wiring issues in the sensor circuit, exhaust leaks, engine misfires, or a malfunctioning powertrain control module (PCM).

4. How can I diagnose the OBDII code P0138 on my 2012 Nissan Altima Sedan?

Diagnose the code by checking the oxygen sensor wiring for damage, inspecting for exhaust leaks, testing the sensor's voltage output, and scanning for any additional trouble codes.

5. Can I continue driving my 2012 Nissan Altima Sedan with the P0138 code?

It is not recommended to drive the vehicle for an extended period with the P0138 code illuminated, as it can lead to decreased fuel efficiency and potential damage to the catalytic converter.

6. How can I repair the HO2S12 circuit high voltage issue in my 2012 Nissan Altima Sedan?

Repair options include replacing the faulty oxygen sensor, repairing damaged wiring, fixing exhaust leaks, addressing engine misfires, or reprogramming the PCM if necessary.

7. Will resetting the check engine light fix the P0138 code issue in my 2012 Nissan Altima Sedan?

Resetting the check engine light may temporarily turn it off, but the underlying issue causing the P0138 code will still need to be diagnosed and repaired to prevent further problems.

8. How much does it cost to fix the OBDII code P0138 in a 2012 Nissan Altima Sedan?

The cost of fixing the P0138 code can vary depending on the specific cause, but it typically ranges from $100 to $300 for parts and labor.

9. Can a DIY enthusiast repair the P0138 code on a 2012 Nissan Altima Sedan?

Some aspects of diagnosing and repairing the P0138 code can be tackled by experienced DIY enthusiasts with the right tools and knowledge, but complex issues may require professional help.

10. How often does the OBDII code P0138 occur in 2012 Nissan Altima Sedans?

The P0138 code can occur sporadically in 2012 Nissan Altima Sedans due to various factors like driving conditions, maintenance history, and component wear, but it is not considered a common recurring issue.

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