I have a 2002 Cooper S. The front O2 sensor was replaced 2008 at my expense. The catalytic converter was replaced under emissions warranty 2/09. Now the check engine light is back and dealer says the back O2 sensor needs to be replaced. According to dealer the extended warranty only covers cars produced 10/03 to 11/06. I've tried to read all the related posts and have several questions:

What was the original warranty for the O2 sensors? I've seen 80k/8y mentioned, but don't know if this is accurate? Because if so the front sensor should have been covered before and car still has less than 70k miles.

When the catalytic converter was replaced, should the rear sensor have been replaced then?

Anyone know why Mini wouldn't have covered the 1st year of production in this warranty extension?

 

It sounds like the % of failures never crossed some magical threshold, and who knows, maybe there was a switch suppliers or something.
Checking on what YOUR emmision warreny should not be too hard, check the manual. Usually the emmsion warrenty is a seperate card, because it varries a bit based on where the car was sold. The dealer should be able to tell you.
Try calling 1-800-ask-mini, have your vin# handy. They should be able too look it up and give you the correct answer. Be sure to post back with the info.