AutoCodes – Pontiac – P0139 Pontiac

P0139 Pontiac Code - HO2S Slow Response Bank 1 Sensor 2

Quick Answer

The Powertrain Control Module (PCM) provides a .45 volt reference signal to the Heated Oxygen Sensor (HO2S) through the Bank 1 high signal circuit. Common causes include Faulty Heated Oxygen Sensor (HO2S) Bank 1 Sensor 2, HO2S Bank 1 Sensor 2 harness is open or shorted, HO2S Bank 1 Sensor 2circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0139 Pontiac indicates HO2S Slow Response Bank 1 Sensor 2.
Common causes: Common causes include Faulty Heated Oxygen Sensor (HO2S) Bank 1 Sensor 2, HO2S Bank 1 Sensor 2 harness is open or shorted, HO2S Bank 1 Sensor 2circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

Save to My Repairs Step-by-Step Diagnostic Guide My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 540

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 14, 2021

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0139 Pontiac Description

The Powertrain Control Module (PCM) provides a .45 volt reference signal to the Heated Oxygen Sensor (HO2S) through the Bank 1 high signal circuit. When HO2S is cold, less than 392°F (200°C), the sensor signal voltage will be about .45 volt and PCM will keep the system in an open loop. When HO2S is warm, sensor voltage will swing from rich to lean rapidly, at least one switch every 2 seconds, if PCM is in good control of air/fuel mixture. If the oxygen sensor is slow to respond to changes in exhaust oxygen content, the Diagnostic Trouble Code (DTC) will set.

OBDII Code P0139 Pontiac - HO2S Slow Response Bank 1 Sensor 2 - AutoCodes.com — P0139 Pontiac Code - HO2S Slow Response Bank 1 Sensor 2

What does this mean?

What are the Possible Causes of the DTC P0139 Pontiac?

Faulty Heated Oxygen Sensor (HO2S) Bank 1 Sensor 2
HO2S Bank 1 Sensor 2 harness is open or shorted
HO2S Bank 1 Sensor 2circuit poor electrical connection

How to Fix the DTC P0139 Pontiac?

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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0139 Pontiac 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.

Need more information about the P0139 Pontiac code?

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

Need Help with the Code?

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

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 Pontiac Code

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

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

2. What does the OBDII code P0139 indicate in a Pontiac?

- The P0139 code indicates a slow response from the downstream oxygen sensor (Bank 1 Sensor 2) in the exhaust system of the vehicle.

3. What are the possible causes of the HO2S slow response Bank 1 Sensor 2 code in a Pontiac?

- Possible causes include a faulty oxygen sensor, wiring issues, exhaust leaks, engine misfires, or a malfunctioning catalytic converter.

4. How can I diagnose the cause of the P0139 code in my Pontiac?

- Diagnose by checking the oxygen sensor connections, inspecting the sensor wiring for damage, testing the sensor's voltage output, and examining the exhaust system for leaks or other issues.

5. Can I continue driving my Pontiac with the P0139 trouble code?

- It is not recommended to drive with the P0139 code as it can lead to decreased fuel efficiency, engine performance issues, and potential damage to the catalytic converter.

6. How can I repair the HO2S slow response Bank 1 Sensor 2 code in my Pontiac?

- Repair options may include replacing the oxygen sensor, repairing damaged wiring, fixing exhaust leaks, addressing engine misfires, or replacing the catalytic converter if necessary.

7. Will resetting the check engine light clear the P0139 code in my Pontiac?

- Resetting the check engine light may temporarily clear the code, but if the underlying issue causing the code is not addressed, the light is likely to come back on.

8. Is it necessary to replace the oxygen sensor when dealing with the P0139 code in a Pontiac?

- If the oxygen sensor is determined to be faulty or causing the slow response, it is recommended to replace it to resolve the P0139 code.

9. How important is it to address the P0139 code promptly in a Pontiac?

- It is important to address the P0139 code promptly to prevent potential damage to the engine and catalytic converter, and to ensure optimal vehicle performance and fuel efficiency.

10. Can a DIY enthusiast fix the P0139 code issue in a Pontiac?

- Depending on the individual's mechanical skills and access to tools, a DIY enthusiast may be able to address the P0139 code by following repair guides and instructions, but professional assistance is recommended for accurate diagnosis and repair.