Just wanted to see if there is anybody who had experience on this error.
My 2009 mini cooper base's check engine light turned on and the scanner says its the O2 sensor post catalytic. No change on how
the car runs and idles, just check engine light is on.

Changed part which I got from Mini BMW. Reset the codes and ran for a couple of weeks and check engine light comes back on with the same error.
If anybody had this problem before, I would like to hear what other possible problem spots to look in to with this error.

Thanks.

 

I hate to tell you to change the O2 sensor again, but the one you put in could be a dud.

If replacing it won't help fixing, I think you may also need to replace the pre-cat sensor, too. Ultimately, the two sensors work in conjunction to detect a difference in reading before and after the Catalytic Converter. If both sensors are surely not the culprit, then your last bet should be the catalytic converter itself. Also keep in mind that the O2 sensor errors sometimes will stay there a bit longer, even after you clear the codes. It takes 50-100 miles of driving to arrive at new data and then the computer will dis-engage that error code.

 

I have replaced both pre and post o2 sensors. And in fact this is my second post O2 sensor that I have put in within a couple of weeks because of what you exactly said. The last O2 sensor which I got from BMW Mini just to be sure to get the right part.
But it still comes back after a couple of weeks of driving after I have cleared the code.
If the catalytic converter is bad, there would be another code for that, I think.

 

There couldn't be another code for the catalytic failure because there isn't another sensor on the cat-converter to tell you what's wrong. The purpose of the pre and post cat O2 sensors are there so that they can measure for a difference in reading before and after the catalytic converter process. And it's very simple, the computer simply compares the output signal from the two O2 sensors. Ideally if the catalytic converter is working, then the post cat signal will be significantly lower than the pre cat signal. When the cat fails, or if the cat is not present (as if you have a straight pipe to eliminate the cat converter), then the two signals will read closer to each other. In that case, computer sends a code calling the second sensor faulty because it's supposed to read a nominal output range. In your case, after you have done all that, I think you need to look at your cat converter or seek a leakage somewhere in that section of the exhaust.

 

That makes sense, I'll look into that. Thanks.
Is there a good way to check your catalytic converter that its doing its job?

 

Catalytic converter failure is very uncommon if your car mileage is low. They go out as early as 120k miles, normally these can go up to 200k miles without needing attention. But if they do go out, you'd normally get this rotten egg smell for a few days first. Then once you pass that stage, you won't be able to detect it by smell. I'm sure there are other ways out there to diagnose it, but this is as far as my expertise go. Sorry I can't help any further, good luck, though and hope you get it resolved sooner.

 

Ran my analyzer last night and I got the ff codes. 2AD2 , A0B2 and A0B4.