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P0139 Volkswagen Code - HO2S12 Sensor Circuit Slow Response

Quick Answer

The P0139 diagnostic trouble code (DTC) for Volkswagen vehicles specifically refers to the HO2S12 sensor circuit slow response. Common causes include Faulty HO2S12 sensor, Contaminated sensor (dirt, oil, etc.), Wiring issues (short, open circuit). 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 Volkswagen indicates HO2S12 Sensor Circuit Slow Response.
Common causes
Common causes include Faulty HO2S12 sensor, Contaminated sensor (dirt, oil, etc.), Wiring issues (short, open circuit).
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 08, 2024
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Code P0139 Volkswagen Description

The P0139 diagnostic trouble code (DTC) for Volkswagen vehicles specifically refers to the HO2S12 sensor circuit slow response. HO2S stands for Heated Oxygen Sensor, which is an essential component of the vehicle's emissions control system. The sensor is responsible for measuring the oxygen content in the exhaust gases and providing feedback to the engine control module (ECM) to adjust the air-fuel mixture for optimal combustion. In the case of a slow response from the sensor, it means that the sensor is not reacting quickly enough to changes in the exhaust gas composition, which can lead to performance issues and increased emissions.

OBDII Code P0139 Volkswagen - HO2S12 Sensor Circuit Slow Response
P0139 Volkswagen Code - HO2S12 Sensor Circuit Slow Response

Common Causes of P0139 Volkswagen

  1. Faulty HO2S12 sensor
  2. Contaminated sensor (dirt, oil, etc.)
  3. Wiring issues (short, open circuit)
  4. Malfunctioning ECM
  5. Exhaust system leaks

Symptoms of P0139 Volkswagen

  1. Decreased fuel efficiency
  2. Rough idle or stalling
  3. Engine misfires
  4. Check Engine Light illuminated
  5. Failed emissions test

How to Fix P0139 Volkswagen

  1. Diagnose the issue by using a scan tool to retrieve the specific trouble code and data from the oxygen sensor.
  2. Inspect the wiring and connections for any damage or corrosion. Repair or replace as necessary.
  3. Test the HO2S12 sensor to determine if it is responding slowly. Replace the sensor if it fails the test.
  4. Clear the trouble code and reset the ECM to see if the issue is resolved.
  5. Perform a road test to confirm that the repair has effectively addressed the slow response from the oxygen sensor.

Cost to Fix P0139 Volkswagen

The cost of repairing a HO2S12 sensor circuit slow response code can vary depending on the root cause of the issue and the specific components that need to be replaced. In general, the cost of a new oxygen sensor can range from $50 to $200, with labor costs adding an additional $50 to $150. Overall, the total repair cost for this issue can range from $100 to $350, depending on the vehicle make and model, as well as the shop's labor rates. It's recommended to consult with a certified mechanic or auto repair shop for a more accurate estimate based on your specific situation.

What does this mean?

Tech Notes for P0139 Volkswagen

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 Volkswagen Code

1. What are the common symptoms of OBDII code P0139 in a Volkswagen?

- Common symptoms include poor fuel economy, rough idling, hesitation during acceleration, and the illumination of the check engine light.

2. What does the HO2S12 sensor circuit slow response mean in relation to OBDII code P0139 in a Volkswagen?

- The code indicates that the oxygen sensor (HO2S12) in bank 1 sensor 2 is responding slower than expected, affecting the air-fuel mixture and engine performance.

3. What are the possible causes of OBDII code P0139 in a Volkswagen?

- Potential causes include a faulty oxygen sensor, wiring issues, exhaust leaks, engine misfires, or issues with the engine control module (ECM).

4. How can I diagnose the HO2S12 sensor circuit slow response in my Volkswagen when OBDII code P0139 is triggered?

- Diagnosis involves inspecting the oxygen sensor wiring, checking for exhaust leaks, performing a visual inspection of the sensor, and using a scan tool to monitor sensor data.

5. Can a dirty or contaminated oxygen sensor trigger OBDII code P0139 in a Volkswagen?

- Yes, a dirty or contaminated oxygen sensor can cause slow response times and trigger code P0139. Cleaning or replacing the sensor may be necessary.

6. What are some repair tips for addressing OBDII code P0139 in a Volkswagen?

- Repair tips include checking and repairing any damaged wiring, ensuring proper sensor installation, addressing exhaust leaks, and clearing the code to see if it returns.

7. Is it safe to continue driving my Volkswagen with OBDII code P0139 present?

- While the vehicle may still be operable, it is recommended to address the issue promptly to prevent potential damage to the catalytic converter and ensure optimal engine performance.

8. Can a DIY enthusiast tackle the repair for OBDII code P0139 in a Volkswagen?

- Depending on the root cause, some DIY enthusiasts with automotive repair experience may be able to address the issue by following repair guides and utilizing basic tools.

9. Will resetting the check engine light make OBDII code P0139 disappear permanently in a Volkswagen?

- Simply resetting the check engine light without addressing the underlying issue causing code P0139 will not make the code disappear permanently; it is likely to reappear.

10. How much can I expect to pay for professional repairs related to OBDII code P0139 in a Volkswagen?

- Repair costs for OBDII code P0139 can vary based on the root cause and labor rates, but expect to pay anywhere from $100 to $300 or more, depending on the needed repairs.

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