Engine-CodesNissan – P0138 2005 Nissan Pathfinder

P0138 2005 Nissan Pathfinder Code - HO2S12 Circuit High Voltage

Quick Answer

The P0138 code for a 2005 Nissan Pathfinder 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, 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 2005 Nissan Pathfinder indicates HO2S12 Circuit High Voltage.
Common causes
Common causes include Faulty HO2S12 sensor, Damaged wiring or connectors in the sensor circuit, 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.
Table of contents Created and updated by William Orellana on Sep 16, 2024
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Code P0138 2005 Nissan Pathfinder Description

The P0138 code for a 2005 Nissan Pathfinder 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 too high, it can lead to incorrect fuel trim adjustments, affecting the engine's performance and emissions.

OBDII Code P0138 2005 Nissan Pathfinder - HO2S12 Circuit High Voltage
P0138 2005 Nissan Pathfinder Code - HO2S12 Circuit High Voltage

Common Causes of P0138 2005 Nissan Pathfinder

  1. Faulty HO2S12 sensor
  2. Damaged wiring or connectors in the sensor circuit
  3. Exhaust leaks near the sensor
  4. ECM software issues
  5. Engine coolant leaks contaminating the sensor

Symptoms of P0138 2005 Nissan Pathfinder

  1. Decreased fuel efficiency
  2. Rough idling or stalling
  3. Engine hesitation or surging
  4. Illuminated check engine light
  5. Increased emissions

How to Fix P0138 2005 Nissan Pathfinder

  1. Begin by using a scan tool to verify the P0138 code and ensure it is not a false alarm.
  2. Inspect the wiring and connectors in the HO2S12 circuit for any damage or corrosion. Repair or replace as needed.
  3. Check for exhaust leaks near the sensor and repair them if present.
  4. Test the HO2S12 sensor's voltage output with a multimeter to determine if it is functioning correctly. Replace the sensor if necessary.
  5. Clear the code from the ECM memory and perform a test drive to ensure the issue has been resolved.

Cost to Fix P0138 2005 Nissan Pathfinder

The typical repair costs for addressing a P0138 code on a 2005 Nissan Pathfinder can range from $150 to $400, depending on the specific cause of the issue and the cost of parts and labor in your area. Keep in mind that diagnostic time and labor rates at auto repair shops can vary, so it's advisable to get a few quotes before proceeding with the repair.

Tech Notes for P0138 2005 Nissan Pathfinder

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 2005 Nissan Pathfinder Code

1. What does OBDII code P0138 on a 2005 Nissan Pathfinder mean?

- OBDII code P0138 for a 2005 Nissan Pathfinder indicates a high voltage condition in the HO2S12 (Heated Oxygen Sensor Bank 1 Sensor 2) circuit.

2. What are the common symptoms of OBDII code P0138 on a 2005 Nissan Pathfinder?

- Common symptoms of code P0138 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 2005 Nissan Pathfinder?

- The main causes of code P0138 can be a faulty oxygen sensor, a damaged or shorted wiring harness, or an issue with the vehicle's engine control module (ECM).

4. How can I diagnose OBDII code P0138 on my 2005 Nissan Pathfinder?

- To diagnose code P0138, you can use an OBDII scanner to retrieve the code, visually inspect the oxygen sensor and its wiring, and perform voltage tests on the sensor.

5. Can I drive my 2005 Nissan Pathfinder with OBDII code P0138?

- It is not recommended to drive your vehicle with code P0138 unresolved, as it can lead to decreased fuel efficiency and potential damage to the catalytic converter.

6. How do I repair OBDII code P0138 on my 2005 Nissan Pathfinder?

- Repairing code P0138 may involve replacing the HO2S12 sensor, repairing or replacing damaged wiring, or resetting the ECM after resolving the underlying issue.

7. Are there any DIY tips for fixing OBDII code P0138 on a 2005 Nissan Pathfinder?

- DIY tips for addressing code P0138 include checking for loose connections, ensuring the sensor is securely mounted, and carefully following the manufacturer's repair procedures.

8. How much does it cost to fix OBDII code P0138 on a 2005 Nissan Pathfinder?

- The cost of fixing code P0138 can vary depending on the root cause, but it may range from $100 to $300 for parts and labor if the oxygen sensor needs replacement.

9. Will resetting the Check Engine Light resolve OBDII code P0138 on a 2005 Nissan Pathfinder?

- Resetting the Check Engine Light without addressing the underlying issue causing code P0138 will not fix the problem; it is essential to diagnose and repair the root cause.

10. Can a mechanic help me with OBDII code P0138 on my 2005 Nissan Pathfinder?

- Yes, a qualified mechanic can diagnose and repair code P0138 on your 2005 Nissan Pathfinder by using specialized tools and expertise to resolve the high voltage issue in the HO2S12 circuit.

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