P2271 Code: O2 Sensor Signal Biased / Stuck Rich Bank 1 Sensor 2

Reviewed by

Richard McCuistian, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Written by CarParts.com Research Team - Updated on September 15th, 2023

Reading Time: 3 minutes
Summary
  • Diagnostic trouble code (DTC) P2271 stands for “O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 2.”  The code registers if your powertrain control module (PCM) receives a signal from your oxygen sensor indicating an incorrect air-fuel ratio in the catalytic converter.
  • The P2271 code refers to the post-catalytic converter oxygen sensor on bank 1, sensor 2. Common causes for this code include a dirty or faulty HO2S2 (Sensor 2), wiring or circuit problems for HO2S2, and incorrect fuel pressure.
  • Common symptoms of the P2271 code include an illuminated malfunction indicator lamp, rough starting, decreased engine performance, and increased fuel consumption.

When using an OBD-II scanner to diagnose your vehicle, you might come across a P2271 code. Here’s everything you need to know about diagnosing and troubleshooting code P2271.

What Does the P2271 Code Mean?

Code P2271 stands for “O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 2.” This generic powertrain code applies to vehicles made 1996 onwards, which can include vehicles from Volkswagen, Dodge, Hyundai, Ford, and Acura.

A P2271 code refers to the post-catalytic converter oxygen sensor on bank 1, sensor 2, which is responsible for monitoring your catalytic converter performance. This code might register if your powertrain control module (PCM) receives a signal from your oxygen sensor indicating an incorrect air-fuel ratio in the catalytic converter. A deviation in the air-fuel ratio inside your catalytic converter can cause some issues in your vehicle, which we’ll discuss in the following sections.

The P2271 code registers if your PCM receives a signal from your oxygen sensor indicating an incorrect air-fuel ratio in the catalytic converter.

If you need help locating the oxygen sensor that might be causing P2271 to register on your OBD device, read our guide about the difference between bank 1 and bank 2.

Note: The definition of code P2271 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition. Some vehicles have a third sensor downstream, which can fail and cause the PCM to register a P2275 code.

What are the Possible Causes of the P2271 Code?

Here are some of the possible causes of a P2271 code:

A bad fuel injector can trigger the code P2271.

What are the Common Symptoms of the P2271 Code?

Some symptoms of this diagnostic trouble code (DTC) might be too subtle to notice. Make sure to pay close attention to your vehicle’s performance, fuel consumption, ignition, and check engine light. If your vehicle exhibits any of the following symptoms, we recommend using a diagnostic scanner to find out what’s causing your vehicle’s problems.

How to Diagnose the P2271 Code

The first and most important step in repairing your vehicle is learning how to diagnose DTCs. A P2271 code is fairly difficult to diagnose because it can be triggered by one or more issues. If you’re uncertain about your automotive skill, you may want to leave the task to a professional. If you’re planning to repair your vehicle on your own, you can use the following video as a reference for troubleshooting your P2271 code. However, we recommend doing some additional research before attempting any repairs, as some vehicles have specific diagnostic procedures.

How to Fix the P2271 Code

A P2271 code has many potential causes. You’ll have to carefully observe your vehicle and follow its recommended diagnostic procedures to pinpoint the underlying cause that’s triggering your DTC.

Some issues have known fixes. Check the internet for technical service bulletins (TSBs) posted by your vehicle’s maker. If you can’t find a TSB for your vehicle, that’s alright. There are plenty of credible OBD-II resources out there for DIYers such as yourself. You can get an ALLDATA single-vehicle subscription, which contains all the information you need to repair your vehicle.
Keep in mind that not all vehicles are the same. Some vehicles have different diagnostic and repair instructions. What may work to resolve a P2271 code in a Ford may not work for a Honda. Make sure to check your vehicle’s repair manual to avoid making mistakes in your repairs. If you don’t have a lot of experience diagnosing DTCs, it’s best to consult a professional mechanic.

About The Authors
Reviewed By Richard McCuistian, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Written By CarParts.com Research Team

Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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CarParts.com Research Team and Richard McCuistian, ASE Certified Master Automobile Technician