AutoCodes – Nissan – P0139 2003 Nissan Sentra

P0139 2003 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 2003 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 3,831

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 2003 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 2003 Nissan Sentra - HO2S12 Slow Response - AutoCodes.com — P0139 2003 Nissan Sentra Code - HO2S12 Slow Response

What does this mean?

What are the Possible Causes of the DTC P0139 2003 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 2003 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 2003 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 2003 Nissan Sentra Code

1. What does the OBDII code P0139 on a 2003 Nissan Sentra mean?

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

2. What are the common symptoms of a P0139 code in a 2003 Nissan Sentra?

- Common symptoms include poor fuel economy, rough idle, hesitation or stalling during acceleration, and an illuminated check engine light.

3. What are the possible causes of a P0139 code on a 2003 Nissan Sentra?

- The P0139 code can be triggered by a faulty downstream oxygen sensor, wiring issues, exhaust leaks, or a problem with the engine's air-fuel mixture.

4. How can I diagnose and repair a P0139 code in my 2003 Nissan Sentra?

- Start by inspecting the downstream oxygen sensor and its wiring for any damage or corrosion. Check for exhaust leaks and ensure proper engine operation. Replace the oxygen sensor if necessary.

5. Can I drive my 2003 Nissan Sentra with a P0139 code?

- It is not recommended to drive the vehicle for an extended period with a P0139 code, as it can lead to decreased fuel efficiency and potential damage to the catalytic converter.

6. How much does it typically cost to fix a P0139 code on a 2003 Nissan Sentra?

- The cost of repairing a P0139 code can vary depending on the root cause of the issue. Replacing the downstream oxygen sensor can cost between $100 to $200, including parts and labor.

7. Will resetting the check engine light fix the P0139 code temporarily?

- Resetting the check engine light may temporarily turn it off, but the underlying issue causing the P0139 code will likely resurface. It is best to diagnose and repair the problem to prevent further complications.

8. Is it possible to prevent the recurrence of a P0139 code on a 2003 Nissan Sentra?

- Regular maintenance, including checking and replacing oxygen sensors as recommended, can help prevent the recurrence of a P0139 code. Ensuring proper engine performance and addressing any exhaust system issues promptly can also help prevent the code from reappearing.

9. Can a P0139 code cause damage to other components of the 2003 Nissan Sentra?

- If left untreated, a P0139 code can lead to decreased fuel efficiency and potential damage to the catalytic converter. It is important to address the issue promptly to prevent further damage to the vehicle.

10. How long does it typically take to repair a P0139 code on a 2003 Nissan Sentra?

- The repair time for a P0139 code can vary depending on the exact cause of the issue and the availability of parts. In most cases, the repair can be completed within a few hours to a day at a professional repair shop.