AutoCodes – Nissan – P0139 2012 Nissan Sentra

P0139 2012 Nissan Sentra 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 Sentra 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 3,067

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 Apr 12, 2019

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

What does this mean?

What are the Possible Causes of the DTC P0139 2012 Nissan Sentra?

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 Sentra?

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 Sentra 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 P0139 2012 Nissan Sentra 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 P0139 2012 Nissan Sentra Code

1. What does the OBDII code P0139 for a 2012 Nissan Sentra indicate?

The code P0139 on a 2012 Nissan Sentra refers to a Slow Response from the downstream oxygen sensor (HO2S12).

2. What are the common symptoms of the HO2S12 Slow Response code in a 2012 Nissan Sentra?

Common symptoms of the P0139 code in a 2012 Nissan Sentra may include poor fuel economy, rough idling, and potential engine misfires.

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

Possible causes of the P0139 code on a 2012 Nissan Sentra include a faulty oxygen sensor, wiring issues, exhaust leaks, or a problem with the engine's fuel system.

4. How can I diagnose the cause of the P0139 code on my 2012 Nissan Sentra?

Diagnosing the P0139 code on a 2012 Nissan Sentra involves inspecting the oxygen sensor and its wiring, checking for exhaust leaks, and testing the engine's fuel system for proper operation.

5. Can I continue driving my 2012 Nissan Sentra with the P0139 code?

It is not recommended to drive your 2012 Nissan Sentra with the P0139 code as it can lead to decreased fuel efficiency and potential damage to the engine over time.

6. How can I repair the HO2S12 Slow Response code on my 2012 Nissan Sentra?

Repairing the P0139 code on a 2012 Nissan Sentra may involve replacing the downstream oxygen sensor, repairing any wiring issues, fixing exhaust leaks, or addressing fuel system problems.

7. Is it possible to reset the OBDII code P0139 on a 2012 Nissan Sentra without repairing the issue?

While you can clear the P0139 code on a 2012 Nissan Sentra with an OBDII scanner, it is important to address the underlying problem to prevent the code from reoccurring.

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

The cost of fixing the P0139 code on a 2012 Nissan Sentra can vary depending on the specific cause of the issue, but it may range from $100 to $300 for parts and labor.

9. Can a DIY enthusiast repair the P0139 code on a 2012 Nissan Sentra?

If you have the necessary tools and experience working on vehicles, you may be able to replace the downstream oxygen sensor or address wiring issues causing the P0139 code on your 2012 Nissan Sentra.

10. How often should I check the oxygen sensors in my 2012 Nissan Sentra to prevent the P0139 code from appearing?

It is recommended to inspect and potentially replace the oxygen sensors in your 2012 Nissan Sentra as part of regular maintenance every 60,000 to 90,000 miles to help prevent the P0139 code from appearing.