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

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.

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:

• Dirty or faulty HO2S2 (Sensor 2)
• Wiring or circuit problem for HO2S2
• Incorrect fuel pressure
• Bad fuel injector
• Failed catalytic converter
• Malfunctioning purge solenoid valve
• Faulty PCM

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.

• Malfunction indicator lamp illuminated, such as a check engine light
• Rough starting
• Decreased engine performance
• Increased fuel consumption

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.