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Engine-Codes – Nissan – P0139 Nissan

P0139 Nissan Code - HO2S12 Slow Response

Quick Answer

The P0139 code for Nissan vehicles refers to a potential issue with the HO2S12 sensor, also known as the downstream oxygen sensor located after the catalytic converter in bank 1. Common causes include Faulty HO2S12 sensor, Wiring issues or poor electrical connections, Exhaust leaks near the sensor. 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 Nissan indicates HO2S12 Slow Response.
Common causes
Common causes include Faulty HO2S12 sensor, Wiring issues or poor electrical connections, Exhaust leaks near the sensor.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 08, 2024
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Code P0139 Nissan Description

The P0139 code for Nissan vehicles refers to a potential issue with the HO2S12 sensor, also known as the downstream oxygen sensor located after the catalytic converter in bank 1. The code indicates that the sensor is not responding quickly enough to changes in the air-fuel mixture, which can lead to a variety of performance issues.

OBDII Code P0139 Nissan - HO2S12 Slow Response
P0139 Nissan Code - HO2S12 Slow Response

Common Causes of P0139 Nissan

  1. Faulty HO2S12 sensor
  2. Wiring issues or poor electrical connections
  3. Exhaust leaks near the sensor
  4. Contaminated sensor due to oil or coolant leaks
  5. Engine mechanical problems affecting sensor performance

Symptoms of P0139 Nissan

  1. Decreased fuel efficiency
  2. Rough idling or stalling
  3. Engine misfires
  4. Illuminated check engine light
  5. Poor acceleration or hesitation

How to Fix P0139 Nissan

  1. Diagnose the root cause of the issue by using a scan tool to monitor the sensor's response and check for any related trouble codes.
  2. Inspect the sensor and its wiring for any visible damage or signs of contamination.
  3. Replace the HO2S12 sensor if it fails to respond within the specified parameters.
  4. Repair any wiring issues or connections if necessary.
  5. Clear the trouble codes and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0139 Nissan

The cost of repairing a P0139 code for a Nissan vehicle can vary depending on the specific cause of the issue and the labor rates in your area. Typically, replacing a downstream oxygen sensor can range from $150 to $300, including parts and labor. Additional costs may apply if wiring repairs or other components need to be addressed. It's recommended to consult with a trusted mechanic or auto repair shop to get an accurate estimate based on your vehicle's make and model.

What does this mean?

Tech Notes for P0139 Nissan

Replacing the Rear Heated Oxygen Sensor Bank 1 usually takes care of the problem.

When is the Code Detected?

The P0139 code is set when the Engine Control Module (ECM) detects that the rear O2 sensor takes more time to respond between rich and lean than the specified time.

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Information for Specific Nissan Models

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 Nissan Code

1. What are the common symptoms of OBDII code P0139 for a Nissan vehicle?

- Common symptoms include poor fuel economy, rough idling, and the illumination of the Check Engine light.

2. What does the OBDII code P0139 for a Nissan indicate?

- This code indicates a slow response from the downstream oxygen sensor (HO2S12) in the exhaust system.

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

- Possible causes include a faulty oxygen sensor, wiring issues, exhaust system leaks, or an engine misfire.

4. How can I diagnose the root cause of OBDII code P0139 in my Nissan?

- A diagnostic scan tool can help pinpoint the issue by monitoring sensor data and checking for any related trouble codes.

5. Can a dirty or contaminated oxygen sensor cause code P0139 in a Nissan?

- Yes, a dirty or contaminated oxygen sensor can lead to a slow response and trigger OBDII code P0139.

6. What is the recommended repair for OBDII code P0139 on a Nissan?

- The typical repair involves replacing the downstream oxygen sensor (HO2S12) and addressing any underlying issues causing the slow response.

7. Is it safe to continue driving my Nissan with OBDII code P0139 illuminated?

- While the vehicle may still be driveable, it is recommended to address the issue promptly to prevent potential damage to the catalytic converter.

8. Can a DIY enthusiast fix OBDII code P0139 on a Nissan?

- Depending on their skill level, a DIY enthusiast may be able to replace the downstream oxygen sensor themselves to resolve the issue.

9. Will resetting the Check Engine light resolve OBDII code P0139 in a Nissan?

- Resetting the light will clear the immediate indication, but the underlying issue causing the code will need to be addressed to prevent its return.

10. How often should the oxygen sensors be inspected in a Nissan to prevent OBDII code P0139?

- It is recommended to inspect and replace oxygen sensors according to the manufacturer's maintenance schedule to prevent issues like code P0139.

Discuss the causes and fixes for P0139 Nissan OBDII Code

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  • The post cat O2 sensor (B1S2) should not switch. It is used to monitor catalyst efficiency. However the ECM will look at how fast the sensor will reach a certain voltage to determine if it is working. P0139 will set if the O2 does not rich this certain voltage in a certain amount of time. Let's say the O2 heater is not working. It would take the O2 too long to reach this predetermined condition and set P0139. You're welcome, Rick Biegler CMAT L1 

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