AutoCodes – Nissan – P0138 2012 Nissan Pathfinder

P0138 2012 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 2012 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 3,514

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 2012 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 2012 Nissan Pathfinder - HO2S12 Circuit High Voltage - AutoCodes.com — P0138 2012 Nissan Pathfinder Code - HO2S12 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0138 2012 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 2012 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 2012 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.

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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 Pathfinder Code

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

- OBDII code P0138 indicates a high voltage condition in the HO2S12 (Heated Oxygen Sensor 1, Bank 1 Sensor 2) circuit of the vehicle.

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

- Common symptoms include poor fuel economy, rough idling, engine hesitation, and an illuminated Check Engine Light.

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

- Possible causes 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 OBDII code P0138 on my 2012 Nissan Pathfinder?

- Diagnosing P0138 involves checking the wiring and connections of the HO2S12 sensor, inspecting for exhaust leaks, and testing the sensor's voltage output.

5. Can I drive my 2012 Nissan Pathfinder with OBDII code P0138?

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

6. How do I repair OBDII code P0138 on a 2012 Nissan Pathfinder?

- Repair options include replacing the HO2S12 sensor, repairing any damaged wiring, fixing exhaust leaks, or reprogramming the ECM if necessary.

7. Is it easy to replace the HO2S12 sensor on a 2012 Nissan Pathfinder?

- Replacing the HO2S12 sensor typically requires basic tools and some mechanical knowledge. It's a task that can be done at home for those with experience working on vehicles.

8. What is the expected cost to fix OBDII code P0138 on a 2012 Nissan Pathfinder?

- The cost of repair can vary depending on the exact cause of the issue. It may range from around $100 for a DIY fix to a few hundred dollars if professional diagnosis and repair are needed.

9. Can a faulty HO2S12 sensor cause other issues in my 2012 Nissan Pathfinder?

- Yes, a faulty HO2S12 sensor can cause drivability issues, reduced fuel efficiency, and potential harm to the catalytic converter if left unrepaired.

10. How often should I check the HO2S12 sensor in my 2012 Nissan Pathfinder to prevent OBDII code P0138?

- It's recommended to include regular sensor checks as part of your vehicle's maintenance routine, especially during scheduled service appointments or if you notice any symptoms of sensor failure.