Error Code P2270 is defined as O2 Sensor Signal Stuck Lean Bank 1 Sensor 2. A problem caused by wiring error, an issue in the HO2S (Heated Oxygen sensor), fuel pressure, injectors, or an intake leak.

This error code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II system, especially those made since 1996 up to present. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.


This code means the Oxygen 1 sensor 2 to the PCM (powertrain control module, also known as ECM or engine control module) is getting too much in the exhaust stream due to an open circuit or defective sensor, causing a lean signal reading to the PCM.

Common Symptoms

As with other error codes, this code activates the Check Engine light and registers the code to the vehicle’s memory system.

With this code, the catalyst code could also be set.

Possible Causes

This error code is caused by a couple of factors, such as the PCM attempting to correct the output by going rich while monitoring the signal, or an error in the wiring or connection caused by damage which results to a lean output.

How to Check

As with most error codes, technicians diagnose this code by using a scan tool to document the code(s) present in the PCM.

Then, they will conduct a pinpoint test as specified by the vehicle’s manufacturer to verify the O2 sensor signal

Lastly, they will disconnect the O2 sensor and check for proper output voltage, as specified for the vehicle by its manufacturer.

How to Fix

Repairs for this code are as easy as its diagnosis. Of course, it requires a thorough diagnosis for a proper repair. Repair procedures include:

  • Replacing the Oxygen sensor
  • Repair of the faulty wiring or connection to the Oxygen sensor assembly
  • Replacing the PCM if it’s causing an open circuit problem

One of the most common mistakes when addressing this code is replacing the O2 sensor before checking for leaks in the exhaust. Thus, it is required to diagnose the exhaust and repair the leaks (or replace) to solve the leaking problem first before replacing the sensor.

This code can be generated by a vehicle that is having an exhaust leak between 1st and 2nd O2 sensors. The added oxygen that enters the exhaust will cause erroneous signals from the sensor that is downstream from the leak.