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Engine-Codes – Nissan – P0138 2009 Nissan Altima Sedan

P0138 2009 Nissan Altima Sedan Code - HO2S12 Circuit High Voltage

Quick Answer

The P0138 diagnostic trouble code (DTC) for a 2009 Nissan Altima Sedan indicates an issue with the HO2S12 (Heated Oxygen Sensor 1 Bank 1 Sensor 2) circuit having high voltage. Common causes include Faulty HO2S12 sensor, Wiring issues such as shorts or open circuits, Exhaust leaks near the sensor. 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 2009 Nissan Altima Sedan indicates HO2S12 Circuit High Voltage.
Common causes
Common causes include Faulty HO2S12 sensor, Wiring issues such as shorts or open circuits, Exhaust leaks near the sensor.
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 2009 Nissan Altima Sedan Description

The P0138 diagnostic trouble code (DTC) for a 2009 Nissan Altima Sedan indicates an issue with the HO2S12 (Heated Oxygen Sensor 1 Bank 1 Sensor 2) circuit having high voltage. The HO2S12 sensor is responsible for monitoring the oxygen content 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 normal, it can lead to various performance issues in the vehicle.

OBDII Code P0138 2009 Nissan Altima Sedan - HO2S12 Circuit High Voltage
P0138 2009 Nissan Altima Sedan Code - HO2S12 Circuit High Voltage

Common Causes of P0138 2009 Nissan Altima Sedan

  1. Faulty HO2S12 sensor
  2. Wiring issues such as shorts or open circuits
  3. Exhaust leaks near the sensor
  4. Engine running rich due to a malfunctioning fuel injector
  5. ECM software or hardware issues

Symptoms of P0138 2009 Nissan Altima Sedan

  1. Decreased fuel efficiency
  2. Rough idling or engine misfires
  3. Hesitation or lack of power during acceleration
  4. Engine stalling
  5. Check Engine Light illuminated on the dashboard

How to Fix P0138 2009 Nissan Altima Sedan

  1. Use an OBD-II scanner to confirm the P0138 code and diagnose the specific cause of the high voltage reading.
  2. Inspect the wiring harness and connector for any damage or corrosion. Repair or replace as necessary.
  3. Test the HO2S12 sensor using a multimeter to check for proper voltage output. Replace the sensor if it is faulty.
  4. Check for exhaust leaks near the sensor and repair them to prevent false readings.
  5. Clear the DTC and perform a test drive to ensure the issue has been resolved.

Cost to Fix P0138 2009 Nissan Altima Sedan

The typical repair costs for addressing a P0138 code on a 2009 Nissan Altima Sedan can range from $150 to $400, depending on the cause of the issue and the cost of parts and labor. It's important to note that diagnostic time and labor rates at auto repair shops can vary, so it's advisable to check with local shops for a more accurate estimate. Additionally, the cost may be higher if the repair requires more extensive work or the replacement of expensive components.

What does this mean?

Tech Notes for P0138 2009 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 2009 Nissan Altima Sedan Code

1. What does the OBDII code P0138 for a 2009 Nissan Altima Sedan mean?

- The code P0138 indicates that the HO2S12 (heated oxygen sensor 2, bank 1 sensor 2) circuit has detected high voltage.

2. What are the common symptoms of the P0138 code in a 2009 Nissan Altima Sedan?

- Common symptoms may include poor fuel economy, rough idling, engine misfires, and the illumination of the check engine light.

3. What are the possible causes of the P0138 code in a 2009 Nissan Altima Sedan?

- The code P0138 can be triggered by a faulty oxygen sensor, wiring issues in the sensor circuit, exhaust leaks, or an engine running rich.

4. How can I diagnose the P0138 code in my 2009 Nissan Altima Sedan?

- Diagnosing the P0138 code typically involves testing the oxygen sensor, inspecting the wiring for damage or corrosion, and checking for exhaust leaks.

5. Can I drive my 2009 Nissan Altima Sedan with the P0138 code?

- It is not recommended to drive your vehicle with the P0138 code present, as it can lead to poor engine performance and potential damage if left unresolved.

6. How do I repair the P0138 code in my 2009 Nissan Altima Sedan?

- Repairing the P0138 code may involve replacing the HO2S12 sensor, repairing damaged wiring, fixing exhaust leaks, or addressing any issues causing the engine to run rich.

7. Is it possible to reset the P0138 code in a 2009 Nissan Altima Sedan without fixing the underlying issue?

- While you can clear the code with an OBDII scanner, it is crucial to address the root cause of the problem to prevent further issues and ensure proper vehicle operation.

8. How much does it cost to repair the P0138 code in a 2009 Nissan Altima Sedan?

- The cost of repairing the P0138 code can vary depending on the specific issue, but it may range from $100 to $300 for parts and labor.

9. Can a DIY enthusiast fix the P0138 code in a 2009 Nissan Altima Sedan?

- Depending on your skill level and access to tools, DIY enthusiasts may be able to address the P0138 code by replacing the oxygen sensor or repairing wiring issues.

10. How often does the P0138 code occur in a 2009 Nissan Altima Sedan?

- The P0138 code can occur sporadically or persistently, and its frequency may vary depending on the vehicle's condition and maintenance history.

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