AutoCodes – Nissan – P0139 2008 Nissan Altima Sedan

P0139 2008 Nissan Altima Sedan 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 Altima Sedan 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 3,503

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

What does this mean?

What are the Possible Causes of the DTC P0139 2008 Nissan Altima Sedan?

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 Altima Sedan?

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 Altima Sedan 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 Altima Sedan Code

1. What is the meaning of OBDII code P0139 on a 2008 Nissan Altima Sedan?

Code P0139 indicates a slow response from the downstream oxygen sensor (HO2S12) in bank 1 of the exhaust system.

2. What are the common symptoms of code P0139 on a 2008 Nissan Altima Sedan?

Common symptoms include poor fuel economy, rough idling, decreased engine performance, and an illuminated check engine light.

3. What are the possible causes of OBDII code P0139 on a 2008 Nissan Altima Sedan?

Possible causes of code P0139 include a faulty oxygen sensor, wiring issues, exhaust leaks, engine misfires, or a malfunctioning catalytic converter.

4. How can I diagnose the cause of code P0139 on my 2008 Nissan Altima Sedan?

Diagnosing code P0139 typically involves inspecting the oxygen sensor, checking for wiring faults, conducting a visual inspection of the exhaust system, and performing a scan tool test.

5. Can a bad oxygen sensor cause code P0139 on a 2008 Nissan Altima Sedan?

Yes, a faulty downstream oxygen sensor (HO2S12) can trigger code P0139 due to its slow response in monitoring the exhaust gases.

6. How can I repair OBDII code P0139 on my 2008 Nissan Altima Sedan?

Repairing code P0139 may involve replacing the downstream oxygen sensor, repairing any damaged wiring, fixing exhaust leaks, addressing engine misfires, or replacing a malfunctioning catalytic converter.

7. Is it safe to continue driving with OBDII code P0139 on a 2008 Nissan Altima Sedan?

It is generally not recommended to drive with a malfunctioning oxygen sensor, as it can lead to decreased fuel efficiency and potentially cause damage to other engine components.

8. Will resetting the check engine light resolve OBDII code P0139 on a 2008 Nissan Altima Sedan?

Simply resetting the check engine light will not fix the underlying issue causing code P0139. It is important to diagnose the problem and perform the necessary repairs.

9. How much does it cost to repair OBDII code P0139 on a 2008 Nissan Altima Sedan?

The cost of repairing code P0139 can vary depending on the underlying issue, but it may range from $100 to $500 or more, including parts and labor.

10. Can a DIY enthusiast fix OBDII code P0139 on a 2008 Nissan Altima Sedan?

While some aspects of diagnosing and repairing code P0139 can be tackled by a DIY enthusiast, it is recommended to seek professional help, especially when dealing with complex issues like sensor replacement or exhaust system repairs.