AutoCodes – BMW – P0139 BMW

P0139 BMW Code - O2 Sensor Circuit Slow Response Bank 1 Sensor 2

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 BMW indicates O2 Sensor Circuit Slow Response Bank 1 Sensor 2.
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 24,310

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 Apr 12, 2019

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0139 BMW 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 BMW - O2 Sensor Circuit Slow Response Bank 1 Sensor 2 - AutoCodes.com — P0139 BMW Code - O2 Sensor Circuit Slow Response Bank 1 Sensor 2

What does this mean?

What are the Possible Causes of the DTC P0139 BMW?

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 BMW?

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 BMW 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 BMW Code

1. What are the common symptoms of OBDII code P0139 on a BMW?

The common symptoms of code P0139 include poor fuel economy, rough idling, and a noticeable decrease in engine performance.

2. What does the OBDII code P0139 "O2 Sensor Circuit Slow Response Bank 1 Sensor 2" mean for a BMW?

This code indicates that the downstream oxygen sensor in Bank 1, Sensor 2 of the BMW's exhaust system is not responding as quickly as expected.

3. What are the possible causes of OBDII code P0139 on a BMW?

Common causes of code P0139 on a BMW include a faulty oxygen sensor, wiring issues, exhaust leaks, or a malfunctioning catalytic converter.

4. How can I diagnose the O2 sensor circuit slow response issue on my BMW?

To diagnose the O2 sensor circuit slow response problem, you can use an OBDII scanner to read the code, visually inspect the sensor and its wiring, and perform tests to check the sensor's response time.

5. Can I drive my BMW with OBDII code P0139?

It is not recommended to drive your BMW with an unresolved P0139 code, as it can lead to further damage to the engine and emissions system. It is best to address the issue promptly.

6. How can I repair OBDII code P0139 on my BMW?

Repairing OBDII code P0139 typically involves replacing the faulty oxygen sensor in Bank 1, Sensor 2, addressing any wiring issues, and ensuring proper connections in the exhaust system.

7. Will resetting the OBDII code P0139 on my BMW make it go away?

Resetting the code may temporarily turn off the check engine light, but if the underlying issue causing P0139 is not fixed, the code is likely to return after some driving cycles.

8. Can a dirty air filter cause OBDII code P0139 on a BMW?

A dirty air filter is unlikely to directly cause code P0139. However, a clogged air filter can affect the air-fuel mixture and engine performance, indirectly leading to issues with the downstream oxygen sensor.

9. How much does it cost to fix OBDII code P0139 on a BMW?

The cost to fix OBDII code P0139 on a BMW can vary depending on the specific cause of the issue, the labor rates at the repair shop, and the cost of parts. It is advisable to get a diagnostic and repair estimate from a qualified mechanic.

10. Can I prevent OBDII code P0139 from appearing on my BMW?

Regular maintenance, such as replacing oxygen sensors at recommended intervals, checking for exhaust leaks, and ensuring proper engine performance, can help prevent OBDII code P0139 and other related issues on your BMW.