AutoCodes – Nissan – P0138 2007 Nissan Pathfinder

P0138 2007 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 2007 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 2,563

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 2007 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 2007 Nissan Pathfinder - HO2S12 Circuit High Voltage - AutoCodes.com — P0138 2007 Nissan Pathfinder Code - HO2S12 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0138 2007 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 2007 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 2007 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 2007 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 2007 Nissan Pathfinder Code

1. What does the OBDII code P0138 for a 2007 Nissan Pathfinder indicate?

The code P0138 refers to the HO2S12 (Heated Oxygen Sensor 1, Bank 1 Sensor 2) Circuit High Voltage.

2. What are the common symptoms of a P0138 code on a 2007 Nissan Pathfinder?

Common symptoms include poor fuel economy, rough idling, engine stalling, and the illuminated Check Engine Light on the dashboard.

3. What are the possible causes of a P0138 code on a 2007 Nissan Pathfinder?

Potential causes include a faulty oxygen sensor, wiring issues in the HO2S12 circuit, exhaust leaks near the sensor, or a problem with the engine's fuel system.

4. How serious is a P0138 code on a 2007 Nissan Pathfinder?

While your vehicle may still be driveable with a P0138 code, it is essential to address it promptly to prevent further damage to the engine and emission control system.

5. How can I diagnose a P0138 code on my 2007 Nissan Pathfinder?

Diagnosis typically involves inspecting the HO2S12 sensor and its wiring for any visible damage, testing the sensor's voltage output, and checking for exhaust leaks near the sensor.

6. Can I drive my 2007 Nissan Pathfinder with a P0138 code?

It is generally not recommended to drive your vehicle extensively with a P0138 code, as it can lead to decreased fuel efficiency and potential damage to the engine over time.

7. How can I repair a P0138 code on a 2007 Nissan Pathfinder?

Repair options may include replacing the HO2S12 sensor, repairing any damaged wiring, fixing exhaust leaks, or addressing issues with the fuel system.

8. Will a P0138 code on a 2007 Nissan Pathfinder affect emissions?

Yes, a P0138 code can impact the emissions output of your vehicle, potentially causing it to fail emissions tests in some regions.

9. How much does it cost to fix a P0138 code on a 2007 Nissan Pathfinder?

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

10. Can I reset the Check Engine Light after fixing a P0138 code on my 2007 Nissan Pathfinder?

Yes, once the underlying issue triggering the P0138 code is resolved, you can reset the Check Engine Light using an OBDII scanner or by disconnecting the car's battery for a few minutes.