Engine-CodesInfiniti – P0139 Infiniti

P0139 Infiniti Code - HO2S12 Slow Response

Quick Answer

The P0139 code for Infiniti vehicles refers to a problem with the HO2S12 sensor, specifically indicating a slow response from this sensor. Common causes include Contaminated or damaged HO2S12 sensor, Faulty sensor heating element, Wiring issues or poor connection to 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 Infiniti indicates HO2S12 Slow Response.
Common causes
Common causes include Contaminated or damaged HO2S12 sensor, Faulty sensor heating element, Wiring issues or poor connection to 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.
Table of contents Created and updated by William Orellana on Sep 07, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code P0139 Infiniti Description

The P0139 code for Infiniti vehicles refers to a problem with the HO2S12 sensor, specifically indicating a slow response from this sensor. The HO2S12 sensor is part of the emissions control system in the vehicle and is responsible for monitoring the oxygen levels in the exhaust gases. This information is crucial for the engine control unit (ECU) to adjust the air-fuel mixture for optimal combustion. A slow response from the sensor can lead to inaccurate readings, resulting in poor engine performance, reduced fuel efficiency, and increased emissions.

OBDII Code P0139 Infiniti - HO2S12 Slow Response
P0139 Infiniti Code - HO2S12 Slow Response

Common Causes of P0139 Infiniti

  1. Contaminated or damaged HO2S12 sensor
  2. Faulty sensor heating element
  3. Wiring issues or poor connection to the sensor
  4. Malfunctioning ECU
  5. Exhaust leaks affecting sensor readings

Symptoms of P0139 Infiniti

  1. Rough idling or engine misfires
  2. Decreased fuel efficiency
  3. Hesitation or lack of power during acceleration
  4. Illumination of the check engine light

How to Fix P0139 Infiniti

  1. Begin by using a diagnostic scanner to confirm the P0139 code and identify the specific issue with the HO2S12 sensor.
  2. Inspect the sensor, wiring, and connector for any visible damage or contamination. Clean or replace the sensor as needed.
  3. Test the sensor heating element to ensure it is functioning properly. Replace if necessary.
  4. Check the wiring for any breaks or shorts, and repair or replace as needed.
  5. Clear the error code from the ECU's memory and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0139 Infiniti

The cost of repairing a P0139 code on an Infiniti vehicle can vary depending on the specific cause of the issue and the labor rates in your area. In general, the cost of replacing an oxygen sensor can range from $200 to $500, including parts and labor. Additional costs may apply if wiring repairs or ECU diagnostics are required. It's recommended to consult with a professional mechanic to get an accurate estimate based on your vehicle's make and model. Labor rates at auto repair shops typically range from $80 to $150 per hour, but can be higher in metropolitan areas or at dealerships.

Tech Notes for P0139 Infiniti

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.

Need more information about the P0139 Infiniti code?

Need more information on how to fix the P0139 Infiniti code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0139 Infiniti code diagnosed by a professional: Find a repair shop in your area

Information for Specific Infiniti 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 Infiniti Code

No Frequently Asked Questions about P0139 Infiniti Code found.

Discuss the causes and fixes for P0139 Infiniti OBDII Code

Code P0139 Infiniti comments

No comments found for this page.