AutoCodes – Nissan – P0139 2007 Nissan Pathfinder

P0139 2007 Nissan Pathfinder Code - HO2S12 Slow Response

Quick Answer

The Heated Oxygen Sensor 2 (HO2S), 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: P0139 2007 Nissan Pathfinder indicates HO2S12 Slow Response.
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 2,266

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 P0139 2007 Nissan Pathfinder Description

The Heated Oxygen Sensor 2 (HO2S), 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 P0139 2007 Nissan Pathfinder - HO2S12 Slow Response - AutoCodes.com — P0139 2007 Nissan Pathfinder Code - HO2S12 Slow Response

What does this mean?

What are the Possible Causes of the DTC P0139 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
Inappropriate fuel pressure
Faulty fuel injectors
Intake air leaks may be faulty
Exhaust gas leaks

How to Fix the DTC P0139 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 P0139 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.

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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 P0139 2007 Nissan Pathfinder Code

1. What does OBDII code P0139 on a 2007 Nissan Pathfinder indicate?

This code, "HO2S12 Slow Response," specifically points to a slow response from the downstream oxygen sensor (Bank 1 Sensor 2) in the exhaust system.

2. What are the common symptoms associated with OBDII code P0139 on a 2007 Nissan Pathfinder?

Common symptoms include poor fuel economy, decreased engine performance, rough idling, and potential issues with emissions.

3. What are the possible causes of OBDII code P0139 on a 2007 Nissan Pathfinder?

Potential causes include a faulty oxygen sensor, wiring or connector issues, exhaust leaks, engine misfires, or problems with the fuel system.

4. How can I diagnose the root cause of OBDII code P0139 on a 2007 Nissan Pathfinder?

Diagnosis typically involves inspecting the oxygen sensor, checking for wiring damage, conducting tests on the sensor's response time, and examining the exhaust system for leaks or other issues.

5. Can I drive my 2007 Nissan Pathfinder with OBDII code P0139?

It is generally not recommended to drive with this code active, as it can lead to poor engine performance and potentially affect other components over time.

6. Is it safe to continue driving if I have already cleared the OBDII code P0139 on my 2007 Nissan Pathfinder?

Clearing the code may temporarily resolve the issue, but if the underlying problem persists, it is advisable to address it promptly to prevent further damage or issues.

7. How can I repair OBDII code P0139 on a 2007 Nissan Pathfinder?

Repair options may include replacing the downstream oxygen sensor, fixing wiring or connector issues, repairing exhaust leaks, resolving engine misfires, or addressing fuel system problems.

8. Can a DIY enthusiast fix OBDII code P0139 on a 2007 Nissan Pathfinder?

Depending on your skill level and access to tools, some DIY enthusiasts may be able to address this code by following proper diagnostic procedures and making necessary repairs.

9. What should I do if OBDII code P0139 persists after attempting repairs on my 2007 Nissan Pathfinder?

If the code persists after repairs, it may be necessary to seek professional assistance to conduct more in-depth diagnostics and potentially identify any underlying issues that were overlooked.

10. How often should I have the oxygen sensors checked on my 2007 Nissan Pathfinder to prevent OBDII code P0139?

Regular maintenance checks, typically during scheduled service intervals or when experiencing symptoms of poor engine performance, can help detect potential issues with the oxygen sensors and prevent codes like P0139.