P2270 – O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 2


The signal being put out by sensor 2 on bank 1 is stuck lean (the sensor has detected too much air).

Main Symptoms:

One of the P2270 code's symptoms is the Check Engine Light
The Check Engine Light coming on might be an indicator of the P2270 trouble code

Possible Causes:

  • Problem with fuel injector
  • Exhaust leak near sensor 2 of bank 1
  • Defective sensor 2 of bank 1
  • Incorrect fuel pressure
  • Leak in engine coolant
  • Defective purge solenoid valve
  • Defective PCM (least likely)

Diagnostic Steps:

  • Visually inspect all wiring harnesses to O2 sensor circuits, especially sensor 1 of bank 1
  • Check for exhaust leaks
  • Using a scan tool, monitor sensor readings and compare with manufacturer specs
  • Proceed to test resistance of sensors and replace as necessary

Read More: OBD2 Codes List: Meaning, Fixes, and Free Download