I recently put a new magnaflow exhaust with a magnaflow cat back and when I was done a week or so later my check engine light came on. I took it to my friends shop and had him run the codes and it said it was an O2 sensor. I purchased a new O2 sensor for before the cat and had it put on. A week or so later the light came back on and had it read, was the same thing. The code is P0-139 oxygen sensor circuit slow to respond bank 1 sensor 2. Every time I clear the code it comes back on within a 100 miles or less.

I am wondering what I can do about this because there is nothing wrong with the car it runs better than it did before but I can't stand a check engine light on.

Is there a way to bypass the sensor or a different O2 sensor I need to buy?

Thanks for any help in advance.

Cory

 

P0139 is a fault code for the O2 sensor after the catalytic converter.

You've confirmed the fault is not intermittent (it returns), so next step is replacement of O2 sensor.

It is interesting that the fault is said to be "slow response" as correct operation of secondary O2 sensor is a slow response to changing O2 conditions. Perhaps it's stuck low or high and never changes.

good luck