Hi there,
First post on here so I hope I include enough information!
So we have a mini one 1.4 2007, R56, 69,000 miles and we've been having unusually high emissions. Initially, the mini came in with the EML on and a code indicating the catalytic converter wasn't doing it's job. We changed the CAT and the O2 sensors but 3 weeks later and it's back with the same code.
After an emissions test, we found the emissions were sky high and infact the CAT won't operate when the emissions are so far out. The engine seems to hunt, the revs drop and rise again ever so slightly, as if the ECU is trying to correct the poor emissions.
We've tried testing various things which might be responsible for a corrupt fuel/air ratio but we've hit a bit of a brick wall. Unusually, it seems if you disturb the system, by unplugging anything such as an 02 sensor, or the coolant temp. sensor etc., the car seems to go into a standard mode and it stops hunting and the emissions are perfect.
Has anyone had this issue or can shed some light onto why this happens/suggestions I'd really appreciate it!
Many thanks, Rhys 
