Engine-CodesNissan – P0139 2002 Nissan Sentra

P0139 2002 Nissan Sentra Code - HO2S12 Slow Response

Quick Answer

The P0139 diagnostic trouble code (DTC) for a 2002 Nissan Sentra refers to a slow response from the downstream oxygen sensor (HO2S12). Common causes include Faulty downstream oxygen sensor, Wiring or connector issues, Exhaust leaks. 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 2002 Nissan Sentra indicates HO2S12 Slow Response.
Common causes
Common causes include Faulty downstream oxygen sensor, Wiring or connector issues, Exhaust leaks.
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.
Table of contents Created and updated by William Orellana on Sep 15, 2024
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Code P0139 2002 Nissan Sentra Description

The P0139 diagnostic trouble code (DTC) for a 2002 Nissan Sentra refers to a slow response from the downstream oxygen sensor (HO2S12). The downstream oxygen sensor is located after the catalytic converter and is responsible for monitoring the efficiency of the catalytic converter and providing feedback to the engine control module (ECM) to adjust the air-fuel mixture for optimal performance and emissions.

OBDII Code P0139 2002 Nissan Sentra - HO2S12 Slow Response
P0139 2002 Nissan Sentra Code - HO2S12 Slow Response

Common Causes of P0139 2002 Nissan Sentra

  1. Faulty downstream oxygen sensor
  2. Wiring or connector issues
  3. Exhaust leaks
  4. Malfunctioning ECM
  5. Contaminated fuel

Symptoms of P0139 2002 Nissan Sentra

  1. Decreased fuel economy
  2. Increased emissions
  3. Rough idling
  4. Hesitation during acceleration
  5. Engine misfires

How to Fix P0139 2002 Nissan Sentra

  1. Diagnose the issue by using a scan tool to retrieve the specific DTC and monitor the downstream oxygen sensor's response time.
  2. Inspect the downstream oxygen sensor, wiring, and connectors for any signs of damage or corrosion.
  3. Repair or replace the downstream oxygen sensor if it is faulty.
  4. Repair any wiring or connector issues.
  5. Clear the DTC and perform a test drive to ensure the issue has been resolved.

Cost to Fix P0139 2002 Nissan Sentra

The typical repair costs for addressing a P0139 code on a 2002 Nissan Sentra can vary depending on the specific cause of the issue. Generally, replacing a downstream oxygen sensor can cost between $100 and $300, including parts and labor. However, additional costs may apply if wiring or connector repairs are needed. It's important to note that diagnosis time and labor rates at auto repair shops can vary, so it's advisable to check with local shops for a more accurate estimate.

Tech Notes for P0139 2002 Nissan Sentra

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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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 2002 Nissan Sentra Code

1. What does the OBDII code P0139 for a 2002 Nissan Sentra indicate?

- The code P0139 stands for "HO2S12 Slow Response," indicating a slow response from the oxygen sensor located after the catalytic converter in bank 1 sensor 2.

2. What are the common symptoms of a P0139 code in a 2002 Nissan Sentra?

- Common symptoms include decreased fuel efficiency, rough idling, engine misfires, and potential hesitation during acceleration.

3. What are the possible causes of a P0139 code in a 2002 Nissan Sentra?

- The causes may include a faulty oxygen sensor, wiring issues, exhaust leaks, a malfunctioning catalytic converter, or an engine misfire.

4. How can I diagnose the P0139 code in a 2002 Nissan Sentra?

- Diagnosing the P0139 code involves inspecting the oxygen sensor and its wiring, checking for exhaust leaks, testing the catalytic converter, and scanning for any other related codes.

5. How can I repair a P0139 code in a 2002 Nissan Sentra?

- Repair options may include replacing the oxygen sensor, repairing or replacing damaged wiring, fixing any exhaust leaks, addressing engine misfires, or replacing the catalytic converter if necessary.

6. Can a P0139 code in a 2002 Nissan Sentra cause damage if left untreated?

- Ignoring the P0139 code may lead to decreased fuel efficiency, potential damage to the catalytic converter, and continued poor engine performance over time.

7. How long does it typically take to repair a P0139 code in a 2002 Nissan Sentra?

- The repair time for a P0139 code can vary depending on the exact cause and complexity of the issue. It could range from a quick sensor replacement to more extensive repairs involving the exhaust system.

8. Is it safe to continue driving a 2002 Nissan Sentra with a P0139 code?

- While the vehicle may still be operable with a P0139 code, it is recommended to address the issue promptly to prevent potential damage to the engine or catalytic converter.

9. Can a P0139 code in a 2002 Nissan Sentra be triggered by a loose gas cap?

- A loose gas cap is unlikely to trigger a P0139 code specifically, as this code is related to the oxygen sensor's slow response after the catalytic converter.

10. Will resetting the OBDII system clear a P0139 code in a 2002 Nissan Sentra?

- Resetting the OBDII system may temporarily clear the code, but if the underlying issue is not addressed, the code is likely to reappear after driving cycles.

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