P0140 - OBD-II Trouble Code

Auto Systems and Repair

Oxygen Sensor Circuit No Activity Detected (Bank 1, Sensor 2)

Our emissions expert has put together the following information about the P0140 fault code. We have also included diagnostic procedures you can take to your repair shop if the mechanic is having difficulty analyzing the code.

OBD II Fault Code

  • OBD II P0140

Fault Code Definition
The Catalyst Monitoring Oxygen Sensor evaluates the rear most Catalytic Converter's emissions-reducing capability. Code P0140 is set when there is no activity in the signal from the Rear Oxygen Sensor.

Symptoms

  • Check Engine Light will illuminate
  • In many cases, no abnormal symptoms may be noticed
  • In some cases, the vehicle will fail an Emissions Test
  • In many cases, the NOx emissions will be elevated

Common Problems That Trigger the P0140 Code

  • Defective Catalytic Converter
  • Faulty Rear Oxygen Sensor wiring or connections

Common Misdiagnoses

  • Oxygen Sensor is replaced when the problem is a defective Catalytic Converter
  • Oxygen Sensor is replaced when the problem is faulty sensor wiring or connections
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