AutoCodes – Nissan – P0138 2010 Nissan Pathfinder

P0138 2010 Nissan Pathfinder Code - HO2S12 Circuit High Voltage

Quick Answer

The Heated Oxygen Sensor 2 (HO2S) (Rear O2 Sensor), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. Common causes include Faulty Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection. 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 2010 Nissan Pathfinder indicates HO2S12 Circuit High Voltage.
Common causes: Common causes include Faulty Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection.
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.

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Code Popularity 2,612

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 25, 2024

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0138 2010 Nissan Pathfinder Description

The Heated Oxygen Sensor 2 (HO2S) (Rear O2 Sensor), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. For optimum catalyst operation, the air fuel mixture (air-fuel ratio) must be maintained near the ideal stoichiometric ratio. The HO2S output voltage changes suddenly in the vicinity of the stoichiometric ratio. The Engine Control Module (ECM) adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric. The HO2S generates a voltage between 0.1 and 0.9 V in response to oxygen in the exhaust gas. If the oxygen in the exhaust gas increases, the air-fuel ratio becomes Lean. The ECM interprets Lean when the HO2S voltage is below 0.45 V. If the oxygen in the exhaust gas decreases, the air-fuel ratio becomes Rich. The ECM interprets Rich when the HO2S voltage is above 0.45 V.

OBDII Code P0138 2010 Nissan Pathfinder - HO2S12 Circuit High Voltage - AutoCodes.com — P0138 2010 Nissan Pathfinder Code - HO2S12 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0138 2010 Nissan Pathfinder?

Faulty Rear Heated Oxygen Sensor Bank 1
Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
Intake air leaks
Exhaust gas leaks
Inappropriate fuel pressure
Faulty fuel injectors

How to Fix the DTC P0138 2010 Nissan Pathfinder?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

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

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0138 2010 Nissan Pathfinder code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0138 2010 Nissan Pathfinder code?

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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 2010 Nissan Pathfinder Code

1. What does the OBDII code P0138 for a 2010 Nissan Pathfinder mean?

The code P0138 indicates a fault in the HO2S12 (Heated Oxygen Sensor 2 Bank 1 Sensor 2) circuit, where the sensor is reporting high voltage.

2. What are the common symptoms of OBDII code P0138 on a 2010 Nissan Pathfinder?

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

3. What are the possible causes of OBDII code P0138 in a 2010 Nissan Pathfinder?

Potential causes of code P0138 include a faulty HO2S12 sensor, wiring issues in the sensor circuit, exhaust leaks, or problems in the engine control module.

4. How can I diagnose the OBDII code P0138 in my 2010 Nissan Pathfinder?

Diagnosing code P0138 involves inspecting the HO2S12 sensor and its wiring, checking for exhaust leaks, and using a scan tool to monitor the sensor's voltage readings.

5. How can I repair the OBDII code P0138 on my 2010 Nissan Pathfinder?

Repairing code P0138 may involve replacing the HO2S12 sensor, repairing or replacing damaged wiring, fixing any exhaust leaks, or reprogramming the engine control module.

6. Can I drive my 2010 Nissan Pathfinder with the OBDII code P0138?

It is not recommended to drive your vehicle with code P0138 present, as it can lead to decreased fuel efficiency and potential engine damage if left unresolved.

7. How much does it typically cost to fix the OBDII code P0138 on a 2010 Nissan Pathfinder?

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

8. Will resetting the check engine light clear the OBDII code P0138 on a 2010 Nissan Pathfinder?

Resetting the check engine light may temporarily turn it off, but if the underlying issue causing code P0138 is not addressed, the light will likely come back on.

9. Are there any preventive measures to avoid OBDII code P0138 in a 2010 Nissan Pathfinder?

Regular maintenance, such as inspecting and replacing oxygen sensors as recommended, checking for exhaust leaks, and addressing engine performance issues promptly, can help prevent code P0138.

10. Can a DIY enthusiast fix the OBDII code P0138 on a 2010 Nissan Pathfinder?

While some aspects of diagnosing and repairing code P0138 may be within reach for DIY enthusiasts, specialized equipment and expertise may be required, so professional assistance is often recommended.