I've been a member for a while and you all helped my partner and I replace the fuel filter with your awesome help! Thank you, Thank you, Thank you. My cherry red and white mini is a 2003 with all the good stuff on it and just now turned 50K miles. But, it has started giving me fits with the Service Engine Soon light and the O2 sensor. Last time it took 2 new sensors in the number 2 position, one from my favorite mechanic and one from the expensive dealership to get it turned off. And now, just over a year later, it is on again. I don't even want to think about doing this again. I really haven't begun my search for help but you are so encouraging to post that I thought I would go ahead and ask. Do any of you have experience with this issue, recurring O2 sensor issues. I have read some things that refer to finding out what the engine issue is that is causing the sensors to have problems, but neither Ed nor I have any ideas about where to look for another issue. Thanks for any help you can give us. Oregonbarb

 

I take it your car is an S?
50,000 miles for an '03 is low, but your catolettic converter is probably showing its age. Bad "CAT"s can throw a few different codes, and mess with the readings from your secondary O2 sensor, making it apear that the sensor is bad.
I would start by looking there.