AutoCodes – Buick – P2271 Buick

P2271 Buick Code - HO2S Signal Stuck Rich Bank 1 Sensor 2

Quick Answer

The Heated Oxygen Sensors (HO2S) are used for fuel control and catalyst monitoring. Common causes include Faulty Heated Oxygen Bank 1 Sensor 2, Heated Oxygen Bank 1 Sensor 2 harness is open or shorted, Heated Oxygen Bank 1 Sensor 2 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: P2271 Buick indicates HO2S Signal Stuck Rich Bank 1 Sensor 2.
Common causes: Common causes include Faulty Heated Oxygen Bank 1 Sensor 2, Heated Oxygen Bank 1 Sensor 2 harness is open or shorted, Heated Oxygen Bank 1 Sensor 2 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.

Save to My Repairs My Repairs

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

Code Popularity 4,760

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 May 28, 2022

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
Add Comment

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

Code P2271 Buick Description

The Heated Oxygen Sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the Engine Control Module (ECM) operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air-to-fuel ratio. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0 - 1, 000 mV. Once sufficient HO2S voltage fluctuation is observed by the ECM, Closed Loop is entered. The ECM uses the HO2S voltage to determine the air-to-fuel ratio. An HO2S voltage that increases toward 1, 000 mV indicates a rich fuel mixture. An HO2S voltage that decreases toward 0 mV indicates a lean fuel mixture.
The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed Loop earlier and the ECM to calculate the air-to-fuel ratio sooner.
The Diagnostic Trouble Code (DTC) will be set when the ECM does not detect an HO2S voltage less than 100 mV before accumulated mass airflow exceeds a calibrated value.

OBDII Code P2271 Buick - HO2S Signal Stuck Rich Bank 1 Sensor 2 - AutoCodes.com — P2271 Buick Code - HO2S Signal Stuck Rich Bank 1 Sensor 2

What does this mean?

What are the Possible Causes of the DTC P2271 Buick?

Faulty Heated Oxygen Bank 1 Sensor 2
Heated Oxygen Bank 1 Sensor 2 harness is open or shorted
Heated Oxygen Bank 1 Sensor 2 circuit poor electrical connection
Low or high fuel system pressure
Fuel contamination
Faulty fuel injectors
Exhaust gas leaks
Engine vacuum leaks

How to Fix the DTC P2271 Buick?

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 Sensors (HO2S) usually takes care of the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P2271 Buick 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 P2271 Buick code?

Need more information on how to fix the P2271 Buick code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P2271 Buick 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 P2271 Buick Code

What does the OBDII code P2271 mean for a Buick?

P2271 on a Buick indicates that the downstream oxygen sensor (Bank 1, Sensor 2) is detecting a consistently rich fuel mixture, meaning there is too much fuel and not enough air in the exhaust gases.

What are the common symptoms of the P2271 code on a Buick?

Symptoms may include the check engine light turning on, reduced fuel efficiency, poor engine performance, and possibly a noticeable fuel smell from the exhaust.

What causes the P2271 code to appear on a Buick?

Common causes include a malfunctioning downstream oxygen sensor, exhaust leaks, a faulty catalytic converter, or issues such as a rich-running engine caused by a bad fuel injector or fuel pressure regulator.

Can I drive my Buick with the P2271 code?

While the car may still be drivable, running the engine with this code for an extended time can lead to catalytic converter damage or increased emissions. It’s best to address the issue promptly.

How is the P2271 code diagnosed on a Buick?

A technician will use a scan tool to read live data from the oxygen sensors, inspect for exhaust leaks, and check for related issues like fuel delivery problems or a failing catalytic converter.

What repairs can fix the P2271 code on a Buick?

Repairs may include replacing the downstream oxygen sensor, fixing exhaust leaks, repairing or replacing the catalytic converter, or addressing any fuel system issues causing a rich condition.

How much does it cost to repair a P2271 code on a Buick?

Costs vary depending on the repair needed. Replacing an oxygen sensor typically costs $150–$300, while catalytic converter repairs can range from $500–$2,000 or more.

Can a dirty air filter cause the P2271 code on a Buick?

A dirty air filter is unlikely to cause this specific code, but it can contribute to an overall rich-running condition, which might indirectly lead to oxygen sensor problems.

Will clearing the P2271 code fix the problem on a Buick?

Clearing the code will turn off the check engine light temporarily, but it won’t resolve the underlying issue. If the problem persists, the code will return.

What tools are needed to fix the P2271 code on a Buick?

Basic tools include an OBDII scanner, a wrench or socket set for sensor removal, and possibly a multimeter for electrical testing. A smoke machine may also be used to locate exhaust leaks.