AutoCodes – Generic – P2271

P2271 Code - O2 Sensor Signal Biased/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 indicates O2 Sensor Signal Biased/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 56,748

How popular is this code, among other codes? Medium

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
Comments
Add Comment

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

Code P2271 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 - O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 2 - AutoCodes.com — P2271 Code - O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 2

What does this mean?

What are the Possible Causes of the DTC P2271?

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?

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.

User Submitted Video

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P2271 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 code?

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

Need Help with the Code?

Get the P2271 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P2271 Acura — Secondary Heated Oxygen Sensor 2 Bank 1 Circuit Signal Stuck Rich
P2271 BMW — O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 2
P2271 Buick — HO2S Signal Stuck Rich Bank 1 Sensor 2
P2271 Cadillac — HO2S Signal Stuck Rich Bank 1 Sensor 2
P2271 Chevrolet — HO2S Signal Stuck Rich Bank 1 Sensor 2
P2271 Chrysler — O2 Sensor 1/2 Signal Biased Rich
P2271 Dodge — O2 Sensor 1/2 Signal Biased Rich
P2271 Ford — Oxygen Sensor Signal Stuck Rich Bank 1 Sensor 2
P2271 GMC — HO2S Signal Stuck Rich Bank 1 Sensor 2
P2271 Honda — Secondary Heated Oxygen Sensor 2 Bank 1 Circuit Signal Stuck Rich
P2271 Hyundai — O2 Sensor Signal Stuck Rich Bank 1 Sensor 2
P2271 Jeep — O2 Sensor 1/2 Signal Biased Rich
P2271 KIA — O2 Sensor Signal Stuck Rich Bank 1 Sensor 2
P2271 Lincoln — Oxygen Sensor Signal Stuck Rich Bank 1 Sensor 2
P2271 Mercedes-Benz — O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 2
P2271 Mercury — Oxygen Sensor Signal Stuck Rich Bank 1 Sensor 2
P2271 Pontiac — HO2S Signal Stuck Rich Bank 1 Sensor 2
P2271 Saturn — HO2S Signal Stuck Rich Bank 1 Sensor 2

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.