AutoCodes – Nissan – P0139 2008 Nissan Pathfinder

P0139 2008 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 2008 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 2,387

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 2008 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 2008 Nissan Pathfinder - HO2S12 Slow Response - AutoCodes.com — P0139 2008 Nissan Pathfinder Code - HO2S12 Slow Response

What does this mean?

What are the Possible Causes of the DTC P0139 2008 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 2008 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 2008 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 2008 Nissan Pathfinder Code

1. What does the OBDII code P0139 on a 2008 Nissan Pathfinder indicate?

The code P0139 for a 2008 Nissan Pathfinder specifically refers to a fault with the HO2S12 sensor, indicating a slow response from the sensor.

2. What are the common symptoms of a HO2S12 slow response issue in a 2008 Nissan Pathfinder?

Common symptoms of a HO2S12 slow response issue include poor fuel efficiency, rough idling, engine misfires, and possibly a noticeable decrease in engine performance.

3. What are the possible causes of the HO2S12 slow response code on a 2008 Nissan Pathfinder?

Potential causes of a HO2S12 slow response code in a 2008 Nissan Pathfinder include a faulty oxygen sensor, wiring issues, exhaust leaks, or a problem with the engine's air-fuel mixture.

4. How can I diagnose the HO2S12 slow response problem in my 2008 Nissan Pathfinder?

Diagnosing a HO2S12 slow response issue typically involves checking the oxygen sensor's wiring, inspecting for exhaust leaks, and using a scan tool to monitor sensor data for proper response times.

5. Can I still drive my 2008 Nissan Pathfinder with the P0139 code present?

While it may be possible to drive your vehicle with the P0139 code present, it is not recommended as it can lead to decreased fuel efficiency and potential engine performance issues.

6. How can I repair a HO2S12 slow response problem in my 2008 Nissan Pathfinder?

Repairing a HO2S12 slow response issue may involve replacing the oxygen sensor, repairing any damaged wiring, fixing exhaust leaks, or addressing any issues with the air-fuel mixture.

7. Is it necessary to reset the OBDII system after repairing the P0139 code on a 2008 Nissan Pathfinder?

Yes, it is recommended to reset the OBDII system after repairing the P0139 code to clear the fault code and ensure that the issue has been resolved successfully.

8. Can a DIY enthusiast fix the HO2S12 slow response problem in a 2008 Nissan Pathfinder?

Depending on the DIY enthusiast's skill level and access to tools, it may be possible to address the HO2S12 slow response problem by following repair guides and using appropriate diagnostic equipment.

9. How much does it typically cost to repair a HO2S12 slow response issue in a 2008 Nissan Pathfinder?

The cost of repairing a HO2S12 slow response problem in a 2008 Nissan Pathfinder can vary depending on the specific cause of the issue, but it may range from $100 to $300 for parts and labor.

10. What steps can I take to prevent the recurrence of the P0139 code on my 2008 Nissan Pathfinder?

To prevent the recurrence of the P0139 code, regular maintenance of the oxygen sensors, monitoring the engine performance, and addressing any issues promptly can help maintain the vehicle's optimal performance.