Hey everyone, first time posting, looking to troubleshoot an issue I'm having.

I have a 2008 Mini Cooper Clubman S and I've just recently taken it to a shop that specializes in these sorts of cars and they've told me that I'm getting a fault on my O2 sensor and that's what's turning the check engine light on, I had the sensor replaced about two months ago and it seems that I'm getting the same error again. Is the issue that it wasn't replaced properly or could it be something else that's causing this error? Any advice at all would be appreciated.

Thanks in advance

 

Did you get the codes from the shop? Did you try amotuer shop for a second opinion?

What is the mileage on the car, carbon buildup status, timing chain status?

 

the car has 103,000 miles. There is a little bit of carbon buildup and I'm not sure about the status of the timing chain