Technical Description
The oxygen sensor circuit is responding slowly (Bank1, Sensor2).
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to OBD-II equipped vehicles. Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
This code pertains to the rear oxygen sensor on the driver’s side. It indicates that the engine’s air-fuel ratio is not being adjusted as expected by the oxygen sensor signal or the ECM. This adjustment may not be occurring as frequently as expected once the engine is warmed up or during normal engine use. Bank 1 refers to the bank of cylinders that contains cylinder #1.
Symptoms
Causes
A code P0139 may indicate one or more of the following:
Possible Solutions
The simplest solution is to reset the code and see if it reappears.
If the code returns, the issue is likely with the rear driver’s side oxygen sensor. It will probably need to be replaced, but you should also consider these potential solutions:
