AutoCodes – Nissan – P0139 2004 Nissan Maxima

P0139 2004 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 2004 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 4,009

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

What does this mean?

What are the Possible Causes of the DTC P0139 2004 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 2004 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 2004 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 2004 Nissan Maxima Code

1. What are the common symptoms of OBDII code P0139 in a 2004 Nissan Maxima?

- Common symptoms include poor fuel economy, rough idling, and decreased engine performance.

2. What does the code P0139 for a 2004 Nissan Maxima mean?

- Code P0139 indicates a slow response from the downstream oxygen sensor (HO2S12) located after the catalytic converter.

3. What are the possible causes of the HO2S12 slow response error in a 2004 Nissan Maxima?

- Causes can include a faulty oxygen sensor, wiring issues, exhaust leaks, or a malfunctioning catalytic converter.

4. How can I diagnose the HO2S12 slow response code in my 2004 Nissan Maxima?

- Diagnose by inspecting the oxygen sensor and its wiring for damage, checking for exhaust leaks, and testing the functionality of the catalytic converter.

5. Is it safe to continue driving my 2004 Nissan Maxima with OBDII code P0139?

- While the vehicle may still be operable, it is recommended to address the issue promptly to prevent further damage to the engine or catalytic converter.

6. Can I fix the HO2S12 slow response code in my 2004 Nissan Maxima myself?

- Depending on your skill level, you may be able to replace the oxygen sensor or repair wiring issues yourself. However, more complex issues may require professional assistance.

7. How much does it cost to repair OBDII code P0139 in a 2004 Nissan Maxima?

- The cost of repair can vary depending on the exact cause of the issue. Replacing an oxygen sensor may cost between $100 to $300, while fixing a catalytic converter can be more expensive.

8. Will resetting the OBDII code P0139 in my 2004 Nissan Maxima make it go away?

- Resetting the code may temporarily clear the error, but it will likely return if the underlying issue is not addressed.

9. Can a dirty air filter cause the HO2S12 slow response code in a 2004 Nissan Maxima?

- While a dirty air filter can affect engine performance, it is not a direct cause of the P0139 code. Focus on checking the oxygen sensor, wiring, and exhaust system for issues.

10. How often should the oxygen sensors be replaced in a 2004 Nissan Maxima to prevent OBDII code P0139?

- Oxygen sensors typically last between 50,000 to 100,000 miles. It's recommended to follow the manufacturer's guidelines for sensor replacement to avoid issues like code P0139.