Skip the auto shop - Our mechanics make house calls
  1. Home
  2. Articles
  3. P2271 OBD-II Trouble Code: O2 Sensor Signal Stuck Rich Bank 1 Sensor 2

P2271 OBD-II Trouble Code: O2 Sensor Signal Stuck Rich Bank 1 Sensor 2

check engine light logo

P2271 trouble code definition

O2 Sensor Signal Stuck Rich Bank 1 Sensor 2

What the P2271 code means

This code indicates the downstream O2 (oxygen sensor) on bank 1 has failed an onboard test run by the PCM (powertrain control module). Bank 1 is the set of cylinders that includes the number one cylinder.

What causes the P2271 code?

The PCM monitors the sensor data on deceleration and expects to see it indicate a lean condition in a specified amount of time. The time frame for this test is different with every manufacturer. If the O2 fails this test, it is assumed the O2 is faulty.

What are the symptoms of the P2271 code?

The only symptom will be a Check Engine Light. Downstream O2 sensors, as indicated by the sensor 2 position, are used to determine if the catalytic converter is operating efficiently. It will not have any effect on drivability of the vehicle.

How does a mechanic diagnose the P2271 code?

For the most part, this code is fairly foolproof as an indicator of a failure. If there are no other codes, the technician will likely just replace the sensor. The PCM is performing the same test the technician would perform manually, although with a different method.

Although, if the technician has reason to believe there are other circumstances that could set this code, he or she should perform the necessary diagnostics to confirm or prove wrong his concern. These concerns would be out of the ordinary circumstances such as customer working on their own vehicle that could have inadvertently set such a code. This example only serves as one example. All other ideas about concerns would be purely speculation.

Common mistakes when diagnosing the P2271 code

Visually inspecting the exhaust system for leaks, the electrical harness for corrosion or other damage is very important and often forsaken. There are numerous other failures that can set this code, although they usually set their own code or codes. These codes should be diagnosed first. At times, but rarely, an actual rich running condition could exist that could set this code. If a technician were to miss such a condition, the O2 sensor could be replaced and not fix the problem.

Identifying which O2 sensor is which is sometimes cumbersome. Replacing the wrong sensor happens at times. Anytime an O2 sensor is replaced, care should be taken when identifying the correct sensor.

How serious is the P2271 code?

This code is not serious to the drivability of the vehicle for the simple reason that this code is usually only an indicator of a bad downstream O2 sensor. Barring other problems that might contribute to the setting of this code, this code is minor.

What repairs can fix the P2271 code?

  • Replace the bank 1 sensor 2 oxygen sensor
  • Repair O2 the bank 1 sensor 2 wiring harness
  • Replace the O2 connector
  • Fix any exhaust leaks
  • Repairing all other drivability codes and issues first
  • Repair the PCM (Not a common failure)

Additional comments for consideration regarding the P2271 code

All O2 sensors do the same thing, they measure the amount of oxygen in the exhaust stream. The more oxygen there is the leaner the vehicle is running. What’s important about this particular code is recognizing where it is mounted in the exhaust system. When an O2 sensor is labeled a downstream sensor, it means it is mounted after the catalytic converter. If this is the case, it is used for emissions and not for the calculation of the air fuel ratio. The O2 operates the same as an upstream O2, but the data it produces is different.

An upstream O2 will oscillate rapidly between 0.1 volts and 0.9 volts indicating the PCM is making rapid changes to the amount of fuel injected in order to maintain the most efficient conditions for the motor.

A downstream O2 will not oscillate rapidly. It should move very slowly in its voltage range indicating the catalytic converter is successfully reducing the amount of HC’s (hydrocarbons) emitted from the exhaust.

Many newer vehicles use an O2 sensor that uses a wider voltage range of 2.0 to 4.0 volts. These sensors are more accurate and are more accurately called air fuel ratio sensors. Although, they are still referred to as O2 sensors.

Need help with a P2271 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.


More related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...
Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...

Related questions

Q: 2009 Nissan Murano has the P0420 trouble code. It says the normal bank 1 issue, but now it says short to VBAT. What is that and how to fix it?

Hi there. From the description you have provided, for your vehicle's P0420 trouble code. I suspect the O2 (Oxygen) sensor you replaced has created an additional concern for your vehicle. Either, the O2 sensor is incorrect by application or is...

Q: My Check Engine Light turns on and off, and the Service Traction Light is on

There are several components that can cause these types of symptoms. Issues that cause poor performance and shaking can be fuel, air, spark, electronic, or mechanical problems. The good news is that the Check Engine Light has come on. This...

Q: P2006 code is present in the computer.

Hi there. With having the code P2006 present, check the intake wiring to the runner control and see if there is a good connection. Also, the runners in the intake could be clogged and needs cleaned out. A leaking or...