AutoCodes – Nissan – P0139 2004 Nissan Altima Sedan

P0139 2004 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 2004 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 3,873

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 2004 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 2004 Nissan Altima Sedan - HO2S12 Slow Response - AutoCodes.com — P0139 2004 Nissan Altima Sedan Code - HO2S12 Slow Response

What does this mean?

What are the Possible Causes of the DTC P0139 2004 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 2004 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 2004 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 2004 Nissan Altima Sedan Code

1. What is OBDII code P0139 on a 2004 Nissan Altima Sedan?

- OBDII code P0139 for a 2004 Nissan Altima Sedan refers to the HO2S12 (Heated Oxygen Sensor Bank 1 Sensor 2) slow response.

2. What are the common symptoms of OBDII code P0139 on a 2004 Nissan Altima Sedan?

- Common symptoms of P0139 may include poor fuel economy, rough idling, stalling, or a check engine light illuminated on the dashboard.

3. What are the possible causes of OBDII code P0139 on a 2004 Nissan Altima Sedan?

- The potential causes of P0139 include a faulty oxygen sensor, wiring issues, exhaust leaks, or a malfunctioning catalytic converter.

4. How serious is OBDII code P0139 on a 2004 Nissan Altima Sedan?

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

5. How can I diagnose OBDII code P0139 on a 2004 Nissan Altima Sedan?

- Diagnosis involves using an OBDII scanner to retrieve the code, inspecting the oxygen sensor and related wiring, and checking for exhaust leaks.

6. Can I still drive my 2004 Nissan Altima Sedan with OBDII code P0139?

- You may still be able to drive the vehicle with P0139, but it is recommended to have it inspected and repaired as soon as possible to prevent further issues.

7. How can I fix OBDII code P0139 on a 2004 Nissan Altima Sedan?

- Repairs for P0139 may involve replacing the HO2S12 sensor, repairing or replacing damaged wiring, fixing exhaust leaks, or addressing catalytic converter issues.

8. Will resetting the check engine light resolve OBDII code P0139 on a 2004 Nissan Altima Sedan?

- Simply resetting the check engine light will not fix the underlying issue causing P0139. The problem should be diagnosed and repaired to prevent the code from reoccurring.

9. How much does it cost to repair OBDII code P0139 on a 2004 Nissan Altima Sedan?

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

10. Can I repair OBDII code P0139 on a 2004 Nissan Altima Sedan myself?

- If you have experience with automotive repairs and the necessary tools, you may be able to address P0139 yourself by following diagnostic procedures and replacing components as needed.