AutoCodes – Nissan – P0139 2008 Nissan Maxima

P0139 2008 Nissan Maxima 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 Maxima 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 2,974

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

What does this mean?

What are the Possible Causes of the DTC P0139 2008 Nissan Maxima?

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 Maxima?

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 Maxima 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 Maxima Code

1. What does OBDII code P0139 on a 2008 Nissan Maxima indicate?

Code P0139 indicates a slow response from the HO2S12 (Heated Oxygen Sensor Bank 1 Sensor 2) in the exhaust system of the vehicle.

2. What are common symptoms of OBDII code P0139 on a 2008 Nissan Maxima?

Common symptoms include poor fuel efficiency, rough idling, hesitation during acceleration, and the illumination of the Check Engine Light.

3. What are potential causes of OBDII code P0139 on a 2008 Nissan Maxima?

Potential causes of code P0139 include a faulty HO2S12 sensor, wiring issues in the sensor circuit, exhaust leaks, or an engine running rich or lean.

4. How can I diagnose the cause of OBDII code P0139 on a 2008 Nissan Maxima?

Diagnosing code P0139 may involve visually inspecting the sensor and its wiring, performing voltage and resistance tests on the sensor, checking for exhaust leaks, and analyzing fuel trim data with a scan tool.

5. Can I continue driving my 2008 Nissan Maxima with OBDII code P0139?

While the vehicle may still be operable with code P0139, it is recommended to address the issue promptly to prevent potential damage to the catalytic converter and ensure optimal performance.

6. How can I repair OBDII code P0139 on a 2008 Nissan Maxima?

Repair options may include replacing the HO2S12 sensor, repairing or replacing damaged wiring, fixing exhaust leaks, addressing any underlying fuel system issues, and clearing the trouble code.

7. Is it possible to reset OBDII code P0139 on a 2008 Nissan Maxima without fixing the issue?

While you can clear the trouble code with an OBDII scanner, it is not recommended to do so without addressing the underlying cause, as the issue may persist and trigger the code again.

8. How much does it cost to fix OBDII code P0139 on a 2008 Nissan Maxima?

The cost of fixing code P0139 can vary depending on the root cause of the issue, the labor rates of the repair shop, and the price of any necessary parts. It is advisable to obtain quotes from different mechanics or dealerships.

9. Can a DIY enthusiast repair OBDII code P0139 on a 2008 Nissan Maxima?

Depending on your skill level and access to tools, DIY enthusiasts may be able to address some aspects of the repair, such as replacing the sensor or fixing minor wiring issues. However, more complex diagnostics and repairs may require professional assistance.

10. How often does OBDII code P0139 occur in a 2008 Nissan Maxima?

Code P0139 can occur sporadically or more frequently depending on the condition of the vehicle, driving habits, and maintenance history. If the issue persists, it is essential to diagnose and address it promptly.