P2272 Code: Oxygen Sensor Signal Biased/Stuck Lean (Bank 2 Sensor 2)

Reading Time: 2 minutes

Oxygen sensors measure how much oxygen remains in the exhaust gases expelled by the engine into the exhaust system. Their readings are sent to the powertrain control module (PCM), which uses the data to adjust the amount of fuel sprayed into the engine.

If the PCM notices that the voltage signals from an oxygen sensor are not shifting as they should, its diagnostics will log a P2272 code.

What Does the P2272 Code Mean?

The Diagnostic Trouble Code (DTC) P2272 indicates “Oxygen Sensor Signal Biased/Stuck Lean (Bank 2 Sensor 2).”

Oxygen sensors emit a voltage signal that changes according to the amount of oxygen in the engine’s exhaust gases. Rich exhaust with low oxygen levels causes the voltage to rise as high as 1,000 millivolts (mV). Conversely, lean exhaust rich in air lowers the voltage to a minimum of 10 mV. At least 10 of these voltage signals are emitted every second.

O2 Sensor Downstream
Oxygen sensors emit a voltage signal that changes according to the amount of oxygen in the engine’s exhaust gases.

The PCM provides a baseline voltage of 450 mV, roughly in the middle of the oxygen sensor’s high and low signal circuits. It also takes samples of the sensors’ voltage signals and compares them to the information stored in its memory. The computer checks how long the voltage stays out of the correct range and counts how many samples go too far.

If most of the voltage samples are much lower than the expected operating range, the PCM will set the powertrain code P2272.

Note: The definition of code P2272 may differ according to the vehicle manufacturer. Check the appropriate repair manual or repair database for the exact code definition.

What are the Common Causes of the P2272 Code?

  • A faulty sensor (oxygen sensor, mass airflow sensor, etc.)
  • Vacuum leak
  • Fuel delivery issues
  • Exhaust leak
  • Issue with the PCM, such as software in need of an update

What are the Common Symptoms of the P2272 Code?

How to Diagnose the P2272 Code

A DTC P2188 is a generic powertrain code that may be logged in vehicles from different auto manufacturers. Vehicles can share apparently similar triggers and symptoms. However, the steps for diagnosis and repair can differ between various makes and models.

If you’re not confident about conducting diagnostic tests on your vehicle, it’s a good idea to bring it to a professional mechanic. Otherwise, you may go ahead and diagnose the issue yourself. To help you get started, here is  a video that may give you an idea of what the process might involve:

How to Fix the P2272 Code

Attempting to fix a P2272 code may become a frustrating task if you don’t have the right tools and know-how to test the oxygen sensor. In most cases, it’s best to leave the job to professionals.
For DIYers with advanced technical knowledge and hands-on experience who prefer to do the job on their own, it will be helpful to rely on the appropriate repair manual or refer to an online repair database.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.

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