AutoCodes – Nissan – P0139 2012 Nissan Pathfinder

P0139 2012 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 2012 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 2,166

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 2012 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 2012 Nissan Pathfinder - HO2S12 Slow Response - AutoCodes.com — P0139 2012 Nissan Pathfinder Code - HO2S12 Slow Response

What does this mean?

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

How to Fix the DTC P0139 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 P0139 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 P0139 2012 Nissan Pathfinder Code

1. What does the OBDII code P0139 on a 2012 Nissan Pathfinder indicate?

This code, also known as HO2S12 Slow Response, indicates a slow response from the downstream oxygen sensor (Bank 1 Sensor 2) in the exhaust system.

2. What are the common symptoms of P0139 on a 2012 Nissan Pathfinder?

Common symptoms include decreased fuel efficiency, rough idling, engine hesitation, and potential stalling.

3. What are the possible causes of the P0139 code on a 2012 Nissan Pathfinder?

Possible causes include a faulty oxygen sensor, wiring issues, exhaust leaks, a vacuum leak, or a problem with the engine's air-fuel mixture.

4. How can I diagnose the P0139 code on my 2012 Nissan Pathfinder?

Diagnosing the P0139 code involves using an OBDII scanner to read the code, inspecting the downstream oxygen sensor and its wiring, checking for exhaust leaks, and ensuring proper air-fuel mixture.

5. Can I drive my 2012 Nissan Pathfinder with the P0139 code?

It is not recommended to drive your vehicle with the P0139 code as it can lead to poor engine performance and potential damage to the catalytic converter.

6. How do I repair the P0139 code on my 2012 Nissan Pathfinder?

Repairing the P0139 code may involve replacing the downstream oxygen sensor, repairing any damaged wiring, fixing exhaust leaks, addressing vacuum leaks, or adjusting the air-fuel mixture.

7. Is it possible to clear the P0139 code on a 2012 Nissan Pathfinder without fixing the issue?

Clearing the code without fixing the underlying issue is not recommended as the problem may persist, leading to further engine issues and potentially failing emissions tests.

8. How much does it cost to repair the P0139 code on a 2012 Nissan Pathfinder?

The cost of repairing the P0139 code can vary depending on the specific issue, but it may range from $100 to $300 for parts and labor.

9. Can a DIY enthusiast fix the P0139 code on a 2012 Nissan Pathfinder?

Depending on your skill level and access to tools, DIY enthusiasts may be able to replace the downstream oxygen sensor or address minor wiring issues to fix the P0139 code.

10. How often does the P0139 code recur after repair on a 2012 Nissan Pathfinder?

If the underlying issue is properly addressed during repair, the P0139 code should not recur frequently. Regular maintenance and inspections can help prevent its reoccurrence.