Hello everyone - I reccently purchased (privet sale) a 2013 R56 Mini Cooper S. I'm having issues with both the down stream and upstream 02 sensors that need to be replaced. following, of course, is the current battery is unregistered and causing issues, according to the diagnostic tool.

My local mini dealership wants $300 for a new battery and to have it registered. Additionally they want $900 to replace the 02 sensors (Firestone wanted $1200 ??)

so basically, I can only afford to do one this month, and the other next month. what would you do? maybe a registered battery would solve the 02 sensor issue?

oh, and I'm pretty sure I need a transmission fluid exchange..