Hi, I just got an '01 turbo two weeks ago and just had a CEL come up. I had a PPI and there were no codes when I bought the car.

Checked it with the OBDII and found this:
P0139 Aging of Oxygen Sensor After Catalytic Converter (Cylinders 1 - 3)
also described as O2 sensor circuit slow response (Bank 1 sensor 2)

Car seems to be running just fine other than the light. My ideas are to either:
1) disconnect the battery and just hope that the code does not come back
2) Clean the MAF? Could this be a possible fix?
3) Buy a new O2 sensor from Amazon, Bosch 16205. But the car only has 46k miles and it seems very early for an o2 sensor to go bad

Any suggestions?

 

Is the car stock or modified?

 

Aging faults on O2 sensors almost always mean you need a new one.
Ben

 

car is stock

 

Replace both the pre cat and the post cat sensor on the driver side. Usually when one fails, the other is not far behind it on that same bank.

Clearing the light is not going to solve the issue, if it came on, there is a problem and the light will just come back on eventually.

 

Thanks for the suggestions