AutoCodes – Nissan – P0139 2005 Nissan Sentra

P0139 2005 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 2005 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 3,965

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 2005 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 2005 Nissan Sentra - HO2S12 Slow Response - AutoCodes.com — P0139 2005 Nissan Sentra Code - HO2S12 Slow Response

What does this mean?

What are the Possible Causes of the DTC P0139 2005 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 2005 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 2005 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 2005 Nissan Sentra Code

1. What does the OBDII code P0139 for a 2005 Nissan Sentra indicate?

The code P0139 indicates a slow response from the downstream oxygen sensor (HO2S12) in the exhaust system of a 2005 Nissan Sentra.

2. What are the common symptoms of a P0139 code in a 2005 Nissan Sentra?

Common symptoms of a P0139 code in a 2005 Nissan Sentra may include reduced fuel efficiency, a rough idling engine, and the illumination of the check engine light.

3. What are the possible causes of a P0139 code in a 2005 Nissan Sentra?

Possible causes of a P0139 code in a 2005 Nissan Sentra include a faulty oxygen sensor, wiring issues, exhaust leaks, or a problem with the engine's air-fuel mixture.

4. How can I diagnose a P0139 code in a 2005 Nissan Sentra?

Diagnosing a P0139 code in a 2005 Nissan Sentra involves using an OBDII scanner to retrieve the code, checking the downstream oxygen sensor's wiring and connections, and inspecting the exhaust system for leaks.

5. Can a P0139 code in a 2005 Nissan Sentra cause other problems if left unaddressed?

If left unaddressed, a P0139 code in a 2005 Nissan Sentra can potentially lead to increased emissions, poor engine performance, and further damage to the catalytic converter.

6. How can I repair a P0139 code in a 2005 Nissan Sentra?

Repairing a P0139 code in a 2005 Nissan Sentra may involve replacing the downstream oxygen sensor, repairing any damaged wiring, fixing exhaust leaks, or addressing issues with the engine's air-fuel mixture.

7. Is it safe to continue driving a 2005 Nissan Sentra with a P0139 code?

It is generally not recommended to continue driving a 2005 Nissan Sentra with a P0139 code, as it can lead to decreased fuel efficiency and potential damage to the catalytic converter.

8. How much does it typically cost to repair a P0139 code in a 2005 Nissan Sentra?

The cost to repair a P0139 code in a 2005 Nissan Sentra can vary depending on the specific issue, but it may range from $100 to $300 for parts and labor.

9. Can I reset the check engine light after fixing a P0139 code in a 2005 Nissan Sentra?

Yes, once you have addressed the underlying issue causing the P0139 code in a 2005 Nissan Sentra, you can reset the check engine light using an OBDII scanner to clear the code.

10. How often does a P0139 code occur in a 2005 Nissan Sentra?

The occurrence of a P0139 code in a 2005 Nissan Sentra can vary depending on factors such as driving conditions, maintenance history, and the overall health of the vehicle's components.