AutoCodes – Nissan – P0139 2009 Nissan Sentra

P0139 2009 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 2009 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 2,705

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 Jun 14, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0139 2009 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 2009 Nissan Sentra - HO2S12 Slow Response - AutoCodes.com — P0139 2009 Nissan Sentra Code - HO2S12 Slow Response

What does this mean?

What are the Possible Causes of the DTC P0139 2009 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 2009 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 2009 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.

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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 2009 Nissan Sentra Code

1. What are the common symptoms of OBDII code P0139 in a 2009 Nissan Sentra?

The common symptoms of code P0139 in a 2009 Nissan Sentra include poor fuel economy, rough idling, hesitation or lack of power during acceleration, and the illumination of the check engine light.

2. What does the OBDII code P0139 "HO2S12 Slow Response" mean in a 2009 Nissan Sentra?

The code P0139 indicates that the oxygen sensor (O2 sensor) located after the catalytic converter in bank 1 sensor 2 (HO2S12) is not responding quickly enough to changes in the air-fuel ratio.

3. What are the possible causes of the HO2S12 slow response code in a 2009 Nissan Sentra?

Common causes of the P0139 code in a 2009 Nissan Sentra include a faulty oxygen sensor, wiring issues in the sensor circuit, exhaust leaks near the sensor, or a malfunctioning catalytic converter.

4. How can I diagnose the P0139 code in my 2009 Nissan Sentra?

Diagnosing the P0139 code involves using an OBDII scanner to retrieve the code, checking the oxygen sensor wiring for damage, inspecting the sensor for proper operation, and looking for any exhaust leaks near the sensor.

5. Can I continue driving my 2009 Nissan Sentra with the P0139 code present?

While you may be able to drive your 2009 Nissan Sentra with the P0139 code, it is not recommended as it can lead to decreased fuel efficiency and potential damage to the catalytic converter over time. It's best to address the issue promptly.

6. How do I repair the HO2S12 slow response code in my 2009 Nissan Sentra?

Repairing the P0139 code typically involves replacing the oxygen sensor in bank 1 sensor 2 (HO2S12) if it is found to be malfunctioning. Ensure all wiring connections are secure and free of damage during the repair process.

7. Is it possible for a dirty or contaminated MAF sensor to trigger the P0139 code in a 2009 Nissan Sentra?

A dirty or contaminated Mass Air Flow (MAF) sensor is not a common cause of the P0139 code. However, it is always good practice to ensure the MAF sensor is clean and functioning properly as part of regular maintenance.

8. How long does it take to repair the P0139 code in a 2009 Nissan Sentra?

The repair time for the P0139 code in a 2009 Nissan Sentra can vary depending on the exact cause of the issue and the expertise of the technician. Generally, it may take anywhere from 1 to 3 hours for diagnosis and repair.

9. Will resetting the OBDII code P0139 in my 2009 Nissan Sentra make it go away permanently?

Resetting the P0139 code in your 2009 Nissan Sentra may temporarily turn off the check engine light, but if the underlying issue causing the code is not addressed, the code is likely to return. It's essential to diagnose and repair the root cause of the problem.

10. Can a DIY enthusiast with basic mechanical skills repair the P0139 code in a 2009 Nissan Sentra?

While some DIY enthusiasts may have the skills to replace the oxygen sensor triggering the P0139 code in a 2009 Nissan Sentra, it is recommended to consult a professional mechanic for an accurate diagnosis and proper repair to ensure the issue is resolved effectively.