Well I was driving home from work yesterday, cruising along in 6th gear...decided to speed up a bit so I gave some gas without shifting, check engine light comes on, Yellow outline of engine half full. Car still drives fine but is lacking "oomph" I motor on and it goes off for a bit, then comes back on after I accelerate up an exit ramp. Stays on until i pull off to the side, shut down and restart. Then later last night i go back out for a ride, same thing again, then when I turn Sport mode off the CEL goes off! Turn sport mode back on and everything is fine. Hasn't come back on since...but has me worried. I'm calling the service dept in a bit to see what they say. I've only had the car since friday night! GARR! Then again, what if the light doesn't come back on? Will it have stored the code in memory so they can see why it came on at all before?

 

Well hasn't come back since, and the service department told me that if it was running a little rich it could have temporarily tripped a sensor or something. I'm not worried about it since it hasn't happened again since. Almost 700 miles on the car total now...the noisy idle is a little odd though. A rhythmic tapping noise only at idle, even after warmed up. It idles smooth, just that odd noise that's all.

 

The injectors tap loudly; get used to that.
Maintain a log of your own on the CEL and make sure to keep reporting it to the dealer.
Check for fuel vapor odors near the bonnet about 5 minutes after you shut the car off. My first R56 had some sort of fuel delivery problem that MINI could never sort out; it was rare but hazardous.

 

I have no idea about the MINI, but on my turbocharged diesel Beetle, high boost will put it in limp mode. Punching the throttle in Sport mode might have done this. Even without a CEL you might still have an error code stored that you could read yourself with a code reader.