02 sensor not ready new OEM o2 sensor no error codes and monitors are ready .

Hello, I’m Pete from the Car Genius team at RepairPal. I’m sorry you’re dealing with this concern on your 2014 Mini Cooper Countryman. With all monitors showing ready except the oxygen sensor and you have already replaced the affected oxygen sensor with a new OEM replacement in some cases this can be due to how the data is being read for that sensor. On many models the oxygen sensor will not show ready until the vehicle is moving or driven, and in some cases with some aftermarket scan tools being plugged into the vehicle data port the sensor may not show ready then until the scan tool is disconnected. I recommend checking into these to see if any of these is causing a concern with it not switching to the ready state and make sure the engine temperature is reading properly as too cold of an engine can sometimes create this as well. It is also a good idea to have the wiring checked over leading to the affected oxygen sensor to see if any wiring concerns are found that need to be repaired or replaced. The last component I can think of that could cause this is that the engine computer itself has an internal electrical fault to where it may need to be replaced. These should all be checked into. If you’d like to find a trusted, certified repair shop in your area, you can check here: https://repairpal.com/certified. If you need more advice, or have any further questions about your vehicle, we’re here to help. Just give us a call at 877-913-1554 where we will be happy to assist!